Delete Doxygen blocks duplicated in both .h and .cpp files.
Fix incorrect argument names in \param blocks. Fix filenames
in \file blocks. Fix broken Doxygen syntax (broken numerated
lists containing more than 9 items, invalid HTML tags, broken
links in \ref and malformed math equations). Wrap code blocks
inside \code ... \endcode.

Features:
   - uses generated pack infos for packing & unpacking directly on GPU
   - can directly send GPU buffers if cuda-enabled MPI is available,
     otherwise the packed buffers are transfered to CPU first
   - communication hiding with cuda streams: communication can be run
     asynchronously - especially useful when compute kernel is also
     split up into inner and outer part

- added RAII classes for CUDA streams and events
- equivalence test that checks if generated CPU and GPU (overlapped)
  versions are computing same result as normal waLBerla LBM kernel