Fix #382 Phase Space Moving Window

Due to ComputationalRadiationPhysics/libSplash#127 the used interface did not reflect the new position
of the GPU in the output. The interface proposed in this pull request saves an `MPI_Allgather` and corrects that issue (see #382).

Internal namings have been updated to fit the new conventions from https://github.com/ComputationalRadiationPhysics/picongpu/issues/128#issuecomment-41366257 .

The meta information for the moving window offset has been added (but this pull does not yet add cropping as planned in #89).