Add Homography multi model fitting check

[johnwlambert]

Per COLMAP section 4.1:

We propose a multi-model geometric verification strategy to augment the scene graph with the appropriate geometric relation. First, we estimate a fundamental matrix. If
at least NF inliers are found, we consider the image pair
as geometrically verified. Next, we classify the transformation by determining the number of homography inliers
NH for the same image pair. To approximate model selection methods like GRIC, we assume a moving camera
in a general scene if NH/NF < HF . For calibrated images, we also estimate an essential matrix and its number
of inliers NE. If NE/NF > EF , we assume correct calibration. In case of correct calibration and NH/NF < HF ,
we decompose the essential matrix, triangulate points from
inlier correspondences, and determine the median triangulation angle αm. Using αm, we distinguish between the
case of pure rotation (panoramic) and planar scenes (planar). 

Pose from homography implemented per COLMAP and this paper: https://hal.inria.fr/inria-00174036/PDF/RR-6303.pdf