Rewrite of the entities in yaspgrid

This is a first draft of an entity in yaspgrid. It is generic
for all codimensions and uses numberings of subentities which
follow the generic reference elements. This way Yasp will support
arbitrary dimension again.
Implement inside() method on the ygrid

To work correctly, it needs a shift to operate with and look
up which is the correct ygridcomponent.
Enumerate the components in the codimension

This implementation is O(2^d). Given that an optimal
algorithm is O(binomial(n over k)) and how small d usually
is, that is feasible.
Give the YaspGeometry a bitset with the unity vectors spanning the geometry

AcisAlignedCubeGeometry asks for such bitset, Yasp has such bitsets.
Change capabilities for entities and communication
[Bugfix] Give the send and recv grids correct index offsets
Update the YGridList container

The previous implementation didnt work with empty
deques in the array of deques and didnt properly
define and end iterator (and operator!=/==)
J
[Cleanup] Prepare the all-entities-yaspgrid for merge
- Add doxygen and incode documentation
- Remove TODO notes
- Remove cobsolete code
Update COPYING