Blender Git Loki

Compute homographies when creating new plane tracker

When new plane tracker is creating, blender will go
over tracked sequence of point tracks, compute homography
between neighbor frames and deform plane rectangle using
this homography.

This makes rectangle plane follow tracked plane quite
nicely. But as an additional homographies will be
updated after corners were slided with a mouse.

Additional changes:

- Display keyframed/tracked information in the cache line
for plane tracks (the same way as it's done for point tracks).
- Fix couple of buys in homography C-API.