Fix #382 Phase Space Moving Window

Due to ComputationalRadiationPhysics/libSplash#127
the interface used did not reflect the new position
of the GPU in the output.
The interfaced used now saves an MPI_Allgather and
corrects that issue.
Make Dump HostBuffer Namings Consistent with #128
Add Meta Info Moving Window Offset

Adds the offset caused by the moving window for the y-direction.
Cropping to the moving window would be better and will follow late on.
Merge pull request #391 from ax3l/fix-psMoving

Fix #382 Phase Space Moving Window