Improve __repr__ for SpectralCube
Added test for __repr__, moved a test up which was in the wrong section (probably following a rebase).
Fix failing test
Add data unit in repr
Added function to render spectral cube
Removed rendering example from yt_wrappers code and add to docs instead
Moved rendering code to docs, and rest of code to to_yt method
Fix line wrap
Merge pull request #47 from astrofrog/to-yt

Provide to_yt() methods to easily interface with yt
Merge pull request #59 from astrofrog/better-repr

Improve __repr__ for SpectralCube
Rename SpectralCubeMask -> BooleanArrayMask
Accept boolean arrays in with_mask

Closes #51
Merge pull request #73 from ChrisBeaumont/mask-refactor

Mask Refactorings
Better error message when units aren't right for closest spectral channel.
Add a code snippet to doc homepage

Closes #62
Merge pull request #76 from ChrisBeaumont/getting-started

Documentation front page improvements
Merge pull request #34 from astrofrog/better-error-spectral-channel

closest_spectral_channel error message can be confusing
Changed radio-tools to radio-astro-tools
Don't import version from package to avoid importing all the dependencies (causes issues for egg_info)
WIP: add conversion between *LINEAR* spectral coordinate systems.  Leaves
MAJOR todo items open.  Not fully implemented due to bug in wcslib or
astropy.wcs