ENH: add SegmentationAdiedRegistration extension s4ext

This module is an improved and expanded version for the 
AFibLongitudinalRegistration - Add extension issue #29

this module is able to perform registration of two grayscale images. In particular, when we want high registration accuracy at certain organ, we can segment them and use the binary masks to aid the registration.

After this is tested, the AFibLongitudinalRegistration - Add extension issue #29 can be closed.