Fix mask slicing for several classes
Merge pull request #56 from astrofrog/fix-mask-slicing

Fix mask slicing for several classes
fix setup.py for py3
uncomment __getitem__....
intermediate commit
slicing masked and unmasked data
fix: no fill for unmasked
remove get_unmasked_data in favor of the slicing approach
hide get_filled_value in favor of the cube.filled_data[slice] approach
make fill_value immutable
implement "with" things
cube sanitization [this may need to be dropped from this branch and
cherry-picked somewhere else]
fix a wrong package use
whitespace
refactor moments to use appropriate slicing tools.
slices -> view everywhere
slices->view in tests
a few more straggler _get_filled_slices
remove apply_mask
automate reader format determination if format==None, and fix related
tests
another get_filled_data... how did I miss that one?  did ack fail me?