This code is to start experiments with global motion models.
The corner detection can be either fast_9 or Harris.
Corner matching is currently based on normalized correlation.
Three flavors of ransac are used to estimate either a
homography (8-param), or an affine model (6-param) or a
rotation-zoom only affine model (4-param).
The highest level API for the library is in vp9_global_motion.h,
where there are two functions - one for computing a single model
and another for computing multiple models up to a maximum number
provided or until a desired inlier probability is achieved.
Change-Id: I3f9788ec2dc0635cbc65f5c66c6ea8853cfcf2dd
