Make color functions used by SLIC 3D-aware
Make more colorconv functions 3D aware
Add initial 3D modifications (not working)
Add function to calculate regularly-spaced grid in nD
Modify SLIC to allow uneven step sizes
Add more descriptive error message to _prepare_colorarray
Separate inner loop of SLIC computation
Bug fixes: concatenation order and shape assignments
Bug fix: don't add singleton dimension to 3D gray images
Bug fix: remove unnecessary __get__ in test_slic
Add 3D slic tests (gray not working yet)
bug fix: 3d test working
Improve PEP8 and Python 3 compliance

Thanks to @JDWarner and @ahojnnes for the input.
PEP8
Always convert image to float in [0, 1]
Rename slic.py to avoid name conflicts
Use educated guesses for presence of color channels in SLIC
Add function to guesstimate number of spatial dimensions
Revert change to is_rgb
Bug fix: add z dimension regardless of multichannel