Rename test_maps_fast -> test_maps.
Clean up tests.

Previously, many of the tests would "pass" if a comm exception was thrown.  These now raise a `unittest.SkipTest` and so are "skipped" if an `InvalidCommSizeError` or `NullCommError` is raised.

Additionally, change instances of `assertEquals` and `assert_` to `assertEqual` and `assertTrue`, as the former are deprecated in Python 3.
`buffer` -> `memoryview` for Python 3.
Inherit from `six`'s `Iterator` for compatible behavior.

Having `GlobalIterator` inherit from `Iterator` and providing a `__next__` method allows the iterator to work in both Python 2 and 3.
Specify integer division for Python3 compatibility.
Specify integer division in maps.
Change `assertEquals` to `assertEqual`.

... because it's deprecated in Python3.
Explicitly expand a zip to a list for Python3 compat.
Small whitespace tweak.
Whitespace.
Remove the `.c` file, which somehow got re-added.