collision-detection

I've been treating tuShorten/tuWiden as a string-ish conversion between UTF16 and UTF 8, so I recommend this.

Here's the code; add it to the end of every tuShorten/tuWiden function.
if (out < (original_out + out_len)) out = 0;

It would be nice to have a crosshair instead of a cursor while aiming for the shot.

We should add an automatic computation of triangle-mesh mass properties.
This would implicitly assume that the TriMesh is manifold and have consistent winding.

That paper suggests that this should be fairly easy to implement, based on the existing code that computes ConvexPolyhedron mass properties.