Fix vai->numFrames never incrementing.

This made it never cache... oops.
Actually, these are draws.  Increase to 24.
Simply don't cache < 100 verts for now.

Fixes wrong vertexes in a number of games.
Don't mark unreliable, just rehash each time.

This improves perf significantly without the bugs.
Merge pull request #666 from unknownbrackets/texcache

Undisable the vertex hash backoff