Add failing test.
Generalize tuple_intersection.
Merge branch 'feature/setitem-slicing' into feature/allow-slice-steps
Fix tuple_intersection for start0 >= start1.

Also, allow passing in a 2-tuple for t0.
Slicing with steps.
Fix a bug.
Add some setitem tests.
Merge branch 'feature/setitem-slicing' into feature/allow-slice-steps
Fix tests.
Merge branch 'feature/setitem-slicing' into feature/allow-slice-steps

Conflicts:
	distarray/dist/maps.py
	distarray/local/maps.py
Merge pull request #395 from enthought/feature/allow-slice-steps

Allow slice steps