Ensure freeing of communicators

Properly free communicators at destruction of MPIShared objects. Expand unit tests to include split communicators and MPI.COMM_SELF.

Small bug fix in setitem

Handle the case of slices with None values (e.g. [:]).

Support setitem syntax in MPIShared

This PR adds support for using square-bracket slice assignment to the MPIShared class. This syntax is still a collective operation and may be slightly slower than using the set() method since it must first do and Allreduce to determine which process has a data input which is not None.

Remove test import

This removes the namespace import of the test subpackage, which explicitly imports mpi4py. The pshmem package can now be imported without triggering an mpi4py import. mpi4py will only be used if a communicator is passed which is not None.

Improved element access

Improved access to local shared memory copy. Updated README.

First automated deployment

0.2.2

Only upload our own project wheels.

More release debugging...

0.2.2a3

Only upload our own project wheels.

Debugging automated upload

0.2.2a2

Switch back to tag deploy.

Debug upload

0.2.2a1

Debugging upload.

Fix upload to PyPI

0.2.1

Fix deployment