File tracking.c became rather huge and annoying to
maintain and it really contains several independent
areas of motrack pipeline.
Now we've got:
* tracking.c: general-purpose functions which are used
by blender, clip editor, RNA and so.
* tracking_detect.c: feature detection functions
(blender-side, logic is still in libmv).
* tracking_plane_tracker.c: blender-side 2D tracking logic.
* tracking_plane_tracker.c: plane track tracker.
* tracking_solver.c: functions for camera solving.
* tracking_stabilize.c: 2D stabilization functions.
* tracking_util.c: utility functions for all those files
and which shouldn't be public.
