Real fix for previous commit from Keir. He's comment;
Real fix for previous commit from Keir. He's comment;

Cleanup for when trackers fall out of the search window.

Sergey originally left a TODO() here, but his fix is the correct
one. I removed the TODO and fixed some comment issues.

petertsoi/libmv,SoylentGraham/libmv,rgkoo/libmv-blender,rgkoo/libmv-blender,petertsoi/libmv,rgkoo/libmv-blender,rgkoo/libmv-blender,petertsoi/libmv,rgkoo/libmv-blender,SoylentGraham/libmv,SoylentGraham/libmv,petertsoi/libmv,SoylentGraham/libmv