Support receiving MPI comm as parameter of KMR()
Support receiving MPI comm as parameter of KMR()

By using a new feature of mpi4py 2.0, MPI communicator can be passed to KMR instance when initializing it.

pf-aics-riken/kmr,pf-aics-riken/kmr,pf-aics-riken/kmr,pf-aics-riken/kmr,pf-aics-riken/kmr,pf-aics-riken/kmr