Merge pull request #29 from pkaifosh/master

segmentation refactoring and testing (with opencv)
Updated segmentation docs
Separate doc pages for Sequence and ImagingDataset
motion correction docs
Extract now working with new 3D sequences
Passed option to save extract summary up to the ImagingDataset.extract()
Merge branch 'master' of github.com:losonczylab/sima
Typo fix in numpy version
Test cases for motion correction with missing data