PEP8 tweaks.
Always use `memoryview` instead of `buffer`.
Add extensive tests to DAP roundtrip test.
Rename `dimdata` function to `_dimdata`...

and add a docstring.
Remove trailing whitespace.
Add a `fromdap` function for importing from DAP [1]_

.. [1] Distributed Array Protocol

All the tests pass except for the last one (which tries to assert that the new `LocalArray`'s data attribute is the same object as the original `LocalArray`'s).  So I assume an unintended copy is happening somewhere.
Split out the failing (identity) assertion...

into its own test.