diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000000000000000000000000000000000000..d5f62a4963b2913d476d09990714868cda8b3c94
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,427 @@
+Attribution-ShareAlike 4.0 International
+
+=======================================================================
+
+Creative Commons Corporation ("Creative Commons") is not a law firm
+and does not provide legal services or legal advice. Distribution of
+Creative Commons public licenses does not create a lawyer-client or
+other relationship. Creative Commons makes its licenses and related
+information available on an "as-is" basis. Creative Commons gives no
+warranties regarding its licenses, any material licensed under their
+terms and conditions, or any related information. Creative Commons
+disclaims all liability for damages resulting from their use to the
+fullest extent possible.
+
+Using Creative Commons Public Licenses
+
+Creative Commons public licenses provide a standard set of terms and
+conditions that creators and other rights holders may use to share
+original works of authorship and other material subject to copyright
+and certain other rights specified in the public license below. The
+following considerations are for informational purposes only, are not
+exhaustive, and do not form part of our licenses.
+
+ Considerations for licensors: Our public licenses are intended
+ for use by those authorized to give the public permission to use
+ material in ways otherwise restricted by copyright and certain
+ other rights. Our licenses are irrevocable. Licensors should read
+ and understand the terms and conditions of the license they
+ choose before applying it. Licensors should also secure all
+ rights necessary before applying our licenses so that the public
+ can reuse the material as expected. Licensors should clearly mark
+ any material not subject to the license. This includes other CC-
+ licensed material, or material used under an exception or
+ limitation to copyright. More considerations for licensors:
+ wiki.creativecommons.org/Considerations_for_licensors
+
+ Considerations for the public: By using one of our public
+ licenses, a licensor grants the public permission to use the
+ licensed material under specified terms and conditions. If the
+ licensor's permission is not necessary for any reason--for
+ example, because of any applicable exception or limitation to
+ copyright--then that use is not regulated by the license. Our
+ licenses grant only permissions under copyright and certain other
+ rights that a licensor has authority to grant. Use of the
+ licensed material may still be restricted for other reasons,
+ including because others have copyright or other rights in the
+ material. A licensor may make special requests, such as asking
+ that all changes be marked or described. Although not required
+ by our licenses, you are encouraged to respect those requests
+ where reasonable. More considerations for the public:
+ wiki.creativecommons.org/Considerations_for_licensees
+
+=======================================================================
+
+Creative Commons Attribution-ShareAlike 4.0 International Public
+License
+
+By exercising the Licensed Rights (defined below), You accept and
+agree to be bound by the terms and conditions of this Creative Commons
+Attribution-ShareAlike 4.0 International Public License ("Public
+License"). To the extent this Public License may be interpreted as a
+contract, You are granted the Licensed Rights in consideration of Your
+acceptance of these terms and conditions, and the Licensor grants You
+such rights in consideration of benefits the Licensor receives from
+making the Licensed Material available under these terms and
+conditions.
+
+
+Section 1 -- Definitions.
+
+ a. Adapted Material means material subject to Copyright and Similar
+ Rights that is derived from or based upon the Licensed Material
+ and in which the Licensed Material is translated, altered,
+ arranged, transformed, or otherwise modified in a manner
+ requiring permission under the Copyright and Similar Rights held
+ by the Licensor. For purposes of this Public License, where the
+ Licensed Material is a musical work, performance, or sound
+ recording, Adapted Material is always produced where the Licensed
+ Material is synched in timed relation with a moving image.
+
+ b. Adapter's License means the license You apply to Your Copyright
+ and Similar Rights in Your contributions to Adapted Material in
+ accordance with the terms and conditions of this Public License.
+
+ c. BY-SA Compatible License means a license listed at
+ creativecommons.org/compatiblelicenses, approved by Creative
+ Commons as essentially the equivalent of this Public License.
+
+ d. Copyright and Similar Rights means copyright and/or similar
+ rights closely related to copyright including, without
+ limitation, performance, broadcast, sound recording, and Sui
+ Generis Database Rights, without regard to how the rights are
+ labeled or categorized. For purposes of this Public License, the
+ rights specified in Section 2(b)(1)-(2) are not Copyright and
+ Similar Rights.
+
+ e. Effective Technological Measures means those measures that, in
+ the absence of proper authority, may not be circumvented under
+ laws fulfilling obligations under Article 11 of the WIPO
+ Copyright Treaty adopted on December 20, 1996, and/or similar
+ international agreements.
+
+ f. Exceptions and Limitations means fair use, fair dealing, and/or
+ any other exception or limitation to Copyright and Similar Rights
+ that applies to Your use of the Licensed Material.
+
+ g. License Elements means the license attributes listed in the name
+ of a Creative Commons Public License. The License Elements of
+ this Public License are Attribution and ShareAlike.
+
+ h. Licensed Material means the artistic or literary work, database,
+ or other material to which the Licensor applied this Public
+ License.
+
+ i. Licensed Rights means the rights granted to You subject to the
+ terms and conditions of this Public License, which are limited to
+ all Copyright and Similar Rights that apply to Your use of the
+ Licensed Material and that the Licensor has authority to license.
+
+ j. Licensor means the individual(s) or entity(ies) granting rights
+ under this Public License.
+
+ k. Share means to provide material to the public by any means or
+ process that requires permission under the Licensed Rights, such
+ as reproduction, public display, public performance,
+ distribution, dissemination, communication, or importation, and
+ to make material available to the public including in ways that
+ members of the public may access the material from a place and at
+ a time individually chosen by them.
+
+ l. Sui Generis Database Rights means rights other than copyright
+ resulting from Directive 96/9/EC of the European Parliament and
+ of the Council of 11 March 1996 on the legal protection of
+ databases, as amended and/or succeeded, as well as other
+ essentially equivalent rights anywhere in the world.
+
+ m. You means the individual or entity exercising the Licensed Rights
+ under this Public License. Your has a corresponding meaning.
+
+
+Section 2 -- Scope.
+
+ a. License grant.
+
+ 1. Subject to the terms and conditions of this Public License,
+ the Licensor hereby grants You a worldwide, royalty-free,
+ non-sublicensable, non-exclusive, irrevocable license to
+ exercise the Licensed Rights in the Licensed Material to:
+
+ a. reproduce and Share the Licensed Material, in whole or
+ in part; and
+
+ b. produce, reproduce, and Share Adapted Material.
+
+ 2. Exceptions and Limitations. For the avoidance of doubt,
+ where Exceptions and Limitations apply to Your use, this
+ Public License does not apply, and You do not need to comply
+ with its terms and conditions.
+
+ 3. Term. The term of this Public License is specified in
+ Section 6(a).
+
+ 4. Media and formats; technical modifications allowed. The
+ Licensor authorizes You to exercise the Licensed Rights in
+ all media and formats whether now known or hereafter
+ created, and to make technical modifications necessary to do
+ so. The Licensor waives and/or agrees not to assert any
+ right or authority to forbid You from making technical
+ modifications necessary to exercise the Licensed Rights,
+ including technical modifications necessary to circumvent
+ Effective Technological Measures. For purposes of this
+ Public License, simply making modifications authorized by
+ this Section 2(a) (4) never produces Adapted Material.
+
+ 5. Downstream recipients.
+
+ a. Offer from the Licensor -- Licensed Material. Every
+ recipient of the Licensed Material automatically
+ receives an offer from the Licensor to exercise the
+ Licensed Rights under the terms and conditions of this
+ Public License.
+
+ b. Additional offer from the Licensor -- Adapted Material.
+ Every recipient of Adapted Material from You
+ automatically receives an offer from the Licensor to
+ exercise the Licensed Rights in the Adapted Material
+ under the conditions of the Adapter's License You
+ apply.
+
+ c. No downstream restrictions. You may not offer or impose
+ any additional or different terms or conditions on, or
+ apply any Effective Technological Measures to, the
+ Licensed Material if doing so restricts exercise of the
+ Licensed Rights by any recipient of the Licensed
+ Material.
+
+ 6. No endorsement. Nothing in this Public License constitutes
+ or may be construed as permission to assert or imply that
+ You are, or that Your use of the Licensed Material is,
+ connected with, or sponsored, endorsed, or granted official
+ status by, the Licensor or others designated to receive
+ attribution as provided in Section 3(a)(1)(A)(i).
+
+ b. Other rights.
+
+ 1. Moral rights, such as the right of integrity, are not
+ licensed under this Public License, nor are publicity,
+ privacy, and/or other similar personality rights; however,
+ to the extent possible, the Licensor waives and/or agrees
+ not to assert any such rights held by the Licensor to the
+ limited extent necessary to allow You to exercise the
+ Licensed Rights, but not otherwise.
+
+ 2. Patent and trademark rights are not licensed under this
+ Public License.
+
+ 3. To the extent possible, the Licensor waives any right to
+ collect royalties from You for the exercise of the Licensed
+ Rights, whether directly or through a collecting society
+ under any voluntary or waivable statutory or compulsory
+ licensing scheme. In all other cases the Licensor expressly
+ reserves any right to collect such royalties.
+
+
+Section 3 -- License Conditions.
+
+Your exercise of the Licensed Rights is expressly made subject to the
+following conditions.
+
+ a. Attribution.
+
+ 1. If You Share the Licensed Material (including in modified
+ form), You must:
+
+ a. retain the following if it is supplied by the Licensor
+ with the Licensed Material:
+
+ i. identification of the creator(s) of the Licensed
+ Material and any others designated to receive
+ attribution, in any reasonable manner requested by
+ the Licensor (including by pseudonym if
+ designated);
+
+ ii. a copyright notice;
+
+ iii. a notice that refers to this Public License;
+
+ iv. a notice that refers to the disclaimer of
+ warranties;
+
+ v. a URI or hyperlink to the Licensed Material to the
+ extent reasonably practicable;
+
+ b. indicate if You modified the Licensed Material and
+ retain an indication of any previous modifications; and
+
+ c. indicate the Licensed Material is licensed under this
+ Public License, and include the text of, or the URI or
+ hyperlink to, this Public License.
+
+ 2. You may satisfy the conditions in Section 3(a)(1) in any
+ reasonable manner based on the medium, means, and context in
+ which You Share the Licensed Material. For example, it may
+ be reasonable to satisfy the conditions by providing a URI
+ or hyperlink to a resource that includes the required
+ information.
+
+ 3. If requested by the Licensor, You must remove any of the
+ information required by Section 3(a)(1)(A) to the extent
+ reasonably practicable.
+
+ b. ShareAlike.
+
+ In addition to the conditions in Section 3(a), if You Share
+ Adapted Material You produce, the following conditions also
+ apply.
+
+ 1. The Adapter's License You apply must be a Creative Commons
+ license with the same License Elements, this version or
+ later, or a BY-SA Compatible License.
+
+ 2. You must include the text of, or the URI or hyperlink to,
+ the Adapter's License You apply. You may satisfy this
+ condition in any reasonable manner based on the medium,
+ means, and context in which You Share Adapted Material.
+
+ 3. You may not offer or impose any additional or different
+ terms or conditions on, or apply any Effective Technological
+ Measures to, Adapted Material that restrict exercise of the
+ rights granted under the Adapter's License You apply.
+
+
+Section 4 -- Sui Generis Database Rights.
+
+Where the Licensed Rights include Sui Generis Database Rights that
+apply to Your use of the Licensed Material:
+
+ a. for the avoidance of doubt, Section 2(a)(1) grants You the right
+ to extract, reuse, reproduce, and Share all or a substantial
+ portion of the contents of the database;
+
+ b. if You include all or a substantial portion of the database
+ contents in a database in which You have Sui Generis Database
+ Rights, then the database in which You have Sui Generis Database
+ Rights (but not its individual contents) is Adapted Material,
+
+ including for purposes of Section 3(b); and c. You must comply
+ with the conditions in Section 3(a) if You Share all or a
+ substantial portion of the contents of the database.
+
+For the avoidance of doubt, this Section 4 supplements and does not
+replace Your obligations under this Public License where the Licensed
+Rights include other Copyright and Similar Rights.
+
+
+Section 5 -- Disclaimer of Warranties and Limitation of Liability.
+
+ a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE
+ EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS
+ AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF
+ ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS,
+ IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION,
+ WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS,
+ ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT
+ KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT
+ ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.
+
+ b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE
+ TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION,
+ NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT,
+ INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES,
+ COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR
+ USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN
+ ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR
+ DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL
+ OR IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.
+
+ c. The disclaimer of warranties and limitation of liability provided
+ above shall be interpreted in a manner that, to the extent
+ possible, most closely approximates an absolute disclaimer and
+ waiver of all liability.
+
+
+Section 6 -- Term and Termination.
+
+ a. This Public License applies for the term of the Copyright and
+ Similar Rights licensed here. However, if You fail to comply with
+ this Public License, then Your rights under this Public License
+ terminate automatically.
+
+ b. Where Your right to use the Licensed Material has terminated
+ under Section 6(a), it reinstates:
+
+ 1. automatically as of the date the violation is cured,
+ provided it is cured within 30 days of Your discovery of the
+ violation; or
+
+ 2. upon express reinstatement by the Licensor.
+
+ For the avoidance of doubt, this Section 6(b) does not affect any
+ right the Licensor may have to seek remedies for Your violations
+ of this Public License.
+
+ c. For the avoidance of doubt, the Licensor may also offer the
+ Licensed Material under separate terms or conditions or stop
+ distributing the Licensed Material at any time; however, doing so
+ will not terminate this Public License.
+
+ d. Sections 1, 5, 6, 7, and 8 survive termination of this Public
+ License.
+
+
+Section 7 -- Other Terms and Conditions.
+
+ a. The Licensor shall not be bound by any additional or different
+ terms or conditions communicated by You unless expressly agreed.
+
+ b. Any arrangements, understandings, or agreements regarding the
+ Licensed Material not stated herein are separate from and
+ independent of the terms and conditions of this Public License.
+
+
+Section 8 -- Interpretation.
+
+ a. For the avoidance of doubt, this Public License does not, and
+ shall not be interpreted to, reduce, limit, restrict, or impose
+ conditions on any use of the Licensed Material that could
+ lawfully be made without permission under this Public License.
+
+ b. To the extent possible, if any provision of this Public License
+ is deemed unenforceable, it shall be automatically reformed to
+ the minimum extent necessary to make it enforceable. If the
+ provision cannot be reformed, it shall be severed from this
+ Public License without affecting the enforceability of the
+ remaining terms and conditions.
+
+ c. No term or condition of this Public License will be waived and no
+ failure to comply consented to unless expressly agreed to by the
+ Licensor.
+
+ d. Nothing in this Public License constitutes or may be interpreted
+ as a limitation upon, or waiver of, any privileges and immunities
+ that apply to the Licensor or You, including from the legal
+ processes of any jurisdiction or authority.
+
+
+=======================================================================
+
+Creative Commons is not a party to its public
+licenses. Notwithstanding, Creative Commons may elect to apply one of
+its public licenses to material it publishes and in those instances
+will be considered the “Licensor.” The text of the Creative Commons
+public licenses is dedicated to the public domain under the CC0 Public
+Domain Dedication. Except for the limited purpose of indicating that
+material is shared under a Creative Commons public license or as
+otherwise permitted by the Creative Commons policies published at
+creativecommons.org/policies, Creative Commons does not authorize the
+use of the trademark "Creative Commons" or any other trademark or logo
+of Creative Commons without its prior written consent including,
+without limitation, in connection with any unauthorized modifications
+to any of its public licenses or any other arrangements,
+understandings, or agreements concerning use of licensed material. For
+the avoidance of doubt, this paragraph does not form part of the
+public licenses.
+
+Creative Commons may be contacted at creativecommons.org.