Plan partitioning for mpi
Fix: no longer assume the index of the first element of a partition is a multiple of the partition size
Adapt coloring for MPI
(OpenMP) remove unused args from generated code
(OpenMP) push color iteration up to python
(OpenMP) add MPI support
add plan debugging code
Add mass2d MPI OpenMP regression test
Fix MPI plan for correct size (exec) of temporary arrays
fix staging construction code
(CUDA) add cpu/gpu transfers for halo exchange
Fix checks for OpenMP halo_exchange_begin
Refactor variable names in Cython plan
OpenMP: Derive FakePlan from _GenericPlan
Make PPlan.echo __str__ method of _GenericPlan
Include pcolors in Plan string representation
Fix invalid partition coloring
Fix remove color dependencies between core/owned/exec_halo partitions