Blender Git Loki

Self intersection detection for gestures.

Two new gestures:

- Merge: remove cuts on a stroke (gesture is a circle around the cuts to remove). The encircled points are changed to continuous points.
- Convert: convert selected strokes to bones (gesture is a stroke that loops back on itself once).

Note that all those different gestures are experimental. First, to get a good hang on recognition. Second, to try different things.