minor
working for cubic blocks

There is a bug, however, for very flat blocks (2D).  Currently under
investigation
arbitrary block dim is working

NOTE: the x/y kernels take different thread block configurations, it is
important that the minimum dimension is at least the number of threads in a
thread block.  There is some spurious behavior if one dimension tends towards 1
node only.
reflecting BC, SB test case
minor
minor
minor
added daint stuff
minor
minor
fixed 2-chunk bug!
fixed binary equvalence problem, some tests
Tidying up, working on GPUkernels.cu
xflux is getting shape
kernels revised
cleaning up, more clear variable names
added chunk dumper
added all ghosts to _dump_chunk
return to xz-case for skew chunks
added file dump at accurate time