Add some 2d tests.
Merge branch 'master' into feature/client-side-from-dimdata

Conflicts:
	distarray/tests/test_client.py
Remove some unused statements.
Rename DenseLocalArray -> LocalArray
Rename `dim_data_per_process` -> `dim_data_per_rank`.
Change references to `iterable` to `sequence`.

It turns out that in `collections.abc`, `sequence` objects support `__getitem__` but `iterable` objects don't.  I need something with a `__getitem__`.
Change docstrings and error messages to use 'rank'

... instead of 'process'.
Merge branch 'master' into feature/client-side-from-dimdata
Resolved merge conflict.