Optimize Cython code
Made circle_line into a cdef function
More optimizations - core.pyx should now be all C functions
Remove unused line
Added missing output type declaration, makes a huge difference!
Added more missing output type declarations
Merge pull request #169 from astrofrog/optimize-cython

Optimize cython
Add segment_photometry
Update segment_photometry docs
Allow label subset for segment_photometry
Change index to labels and make flux nan for invalid labels
Implement error, gain, and mask options in segment_photometry
Implement background option in segment_photometry
Add mask interpolation
WIP: segment_props
Rename segmentation module
WIP: segment_props
WIP: segmentation props
Clean up segment_photometry api docs
Move centroid, area, etc. from segment_photometry to segment_props; more clean up