fix the bugs in the initial commit
spec out subcube
subcube implemented
fix an x/z swap and add tests
implement pyregion-based region extraction
comments only (notes for future dev)
attempts to write tests led to discoveries of issues in the pyregion
tool
the test passes now because it doesn't do anything
add .mean method
fix booleanarraymask broadcasting rules and Slicing - slicing should use
filled_data, not _data
fix tests: kwargs instead of positional args
add a test of boolean array broadcasting
skip multiaxis squash tests if version<1.7
Merge pull request #128 from keflavich/region_extraction

Region extraction