There is no need to call load() on std::atomic if the default memory
order is used.

[doc] make doxygen search for input recursively

See merge request !50

If RECURSIVE is set to NO doxygen will only process files in emper/
when set to YES it will see all files reachable from emper/.

Add emper::getFullVersion()

See merge request !49

This also solves a dependency declaration issue in WorkerSleepExample:
Prior to this change, a clean build could potentially result in

ninja  -C build
ninja: Entering directory `build'
[13/57] Compiling C++ object apps/worker_sleep_example.p/WorkerSleepExample.cpp.o
FAILED: apps/worker_sleep_example.p/WorkerSleepExample.cpp.o
ccache c++ -Iapps/worker_sleep_example.p -Iapps -I../apps -Iemper -I../emper -Iemper/include -I../emper/include -fdiagnostics-color=always -pipe -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Wnon-virtual-dtor -Wextra -Wpedantic -Werror -std=c++17 -O2 -g -Wno-non-virtual-dtor -MD -MQ apps/worker_sleep_example.p/WorkerSleepExample.cpp.o -MF apps/worker_sleep_example.p/WorkerSleepExample.cpp.o.d -o apps/worker_sleep_example.p/WorkerSleepExample.cpp.o -c ../apps/WorkerSleepExample.cpp
../apps/WorkerSleepExample.cpp:12:10: fatal error: emper-version.h: No such file or directory
   12 | #include "emper-version.h"        // for EMPER_FULL_VERSION
      |          ^~~~~~~~~~~~~~~~~
compilation terminated.
[17/57] Generating emper-version.h with a custom command
ninja: build stopped: subcommand failed.
make: *** [Makefile:23: build] Error 1

because worker_sleep_example_exec should have also depend on
emper_version_h. However this is obviously error prone, as users
easily forget to add this dependency. Instead we add
emper::getFullVersion() which is part of the EMPER shared object (not
just of a single header).

Use lib::adt::LockedUnboundedQueue in Scheduler

See merge request !45

Re-use Runtime::getWorkerId() when possible

See merge request !44

Allow an actor to be startet from anywhere

See merge request !43

This class was previously unused, but can be used in Scheduler after
minor modifcations.

Runtime::getWorkerId() may be an expensive operation, hence re-use the
result of the method when possible.

Schedule from anywhere

See merge request !41

In debug builds, the schedule() method is now guarded by an assert(),
as due to this change, the schedule() method will no longer work from
everywhere.

This also improves the worker sleep method.

This directory is used, for example, by clangd.

[gitlab-ci] Bump CI container to flowdalic/debian-testing-dev:1.4

See merge request !40

prevent data races when initializing the workers PRNG seeds

See merge request i4/manycore/emper!38

Each worker currently calls uniformIntDistribution(randomEngine)
which modifies the randomEngine internally and thus produces data races
when the threads run in parallel.

This change calls uniformIntDistribution(randomEngine) on the main thread
for each worker and passes the resulting seeds to the workerLoop.

The data race was found by gcc's tsan.

Add sanitizer CI targets

See merge request i4/manycore/emper!35

Debugging changes

See merge request i4/manycore/emper!37

To exclude debug code from release builds "if constexpr(emper::DEBUG)"
is preferred over "#ifndef NDEBUG".

Revert "[tests] don't undef NDEBUG for test executables"

See merge request i4/manycore/emper!36

This reverts commit b33ac93c.

Now that logging is done independently from NDEBUG, we can re-enable
"undef NDEBUG for test executables". The rationale that we want to
undefine NDEBUG for test executable is that we want, even in release
builds, asserts in tests enabled. Note that this also applies to
asserts in the emper core library, if those are in *headers*.

use DIE* macros instead of the die function

See merge request i4/manycore/emper!33

make logging configurable during compilation and runtime

See merge request i4/manycore/emper!32

    Compile-time:
      * A new meson option 'log_level' is introduced which has all the values from the
        Loglevel enum
      * The 'OFF' option defines EMPER_LOG_OFF which causes the LOG* macros to be empty
        and the Logger<>::log function to return immediately
      * The default 'automatic' option sets 'log_level' to 'Error' for release builds
        and to 'ALL' otherwise

    Runtime:
      * The global variable emper::log_level defined in Debug.hpp controls the logging output
      * It is initialized with the meson option 'log_level' but can be changed during runtime

make the userspace-rcu dependency optional

See merge request i4/manycore/emper!28

Disable the userpace-rcu support by default.
Our used userspace-rcu flavor memb is rather new and not available in
liburcu version 0.10 available in debian buster.
This change switches from using DCE and "if constexpr" to the C
preprocessor so the library is only needed when the userspace-rcu support
is actually enabled.