Removed exportData as property and added a converter for this class
Fixed integration for empty objects.
Fixed name of integrated quantities.

quantity.Discrete: mtimes now uses transpose instead of ctranspose, and transposing is hidden in the names

- setName() for setting names of all elements of a quantity array
- transpose() for transposing quantities: now call by value and change of name
- flipGrid() changes name now

quantity.example: comments

quantity.example: add illustrative example for scalars and a volterra integral of 2nd kind for 2x2 kernels

new: misc.getfield for hierarchical structs, example: myStruct.topLevel.lowerLevel.data == misc.getfield(myStruct, 'topLevel.lowerLevel.data')

- added methods imag() and real()
quantity.Symbolic:
- new method combineGridGridNameVariable() to avoid duplication of code in mathematical operations (mtimes, plus)

quantity: added 'stable' option to unique()-calls. Hence, the order of gridNames is not sorted but remains unchanged in most cases.

- added cumInt() that behaves as Discrete method but only calls int() of Symbolic
- fixed plus for quantities with different variables
- deleted minus since minus in parent class Discrete calls plus() of Symbolic, hence an additional implementation of minus in Symbolic was not necessary.

- previously for gridNames with more than one char, int was called recursivley (for 'zeta', int was called for ('z', 'e', 't', 'a'). Fixed that.
- yet, int does not consider inputs for integral bounds that do not coincide with the bounds of the grid. hence now a assertion informs about that problem if different bounds specified by inputs.

- fixed infinite loop in mtimes()

quantity.Discrete & .Symbolic:
- renamed variables in isConstant() to improve readability

quantity.Discrete & quantity.Symbolic: plus and minus now support quantity and numeric arrays of same size.