Initial commit
Add output paths
Base initialization test case
Pragma once on nonrigid header file
Add skeleton of rigid registration
Class heirarchy
Add exceptions
Calculate sigma2

Matches reference implementation.
Add tolerance parameter
Add max_it
Add outliers argument
Sketch out find_P
Sketch use fgt
Skeleton find_P

First stab at find_P
Use scaling
Rigid implemented, but not normalized
Normalize
Working on rigid registration, but broken

This is a broken commit while I go debug find_P.
Fix find_P, the test may have been bad
Rigid registration is working

Also changes how we return registered points.