Improve collision performance for convex shapes with many edges (edge-edge case is slow)

[erwincoumans]

Currently the GPU SAT clipping implementation for convex-convex collision detection only works fast between convexes with few edges, such as boxes and tetrahedra. Many edge-edge tests slows down the simulation a lot.
We could add a GJK/EPA style collision detection, with persistent contact caches.
Another thing to try it to use the Gauss map optimization, reducing the number of edge-edge cases.

[erwincoumans]

Another idea is to use an LCP solver for the convex collision detection, see the Lemke solver in GPU Gems 3, chapter 33 for example: http://http.developer.nvidia.com/GPUGems3/gpugems3_ch33.html

[erwincoumans]

Why is this issue cluttered with references to other unrelated issues by scrawl and conversy?!?

[erwincoumans]

I will delete this issue and create a new one, just to remove the stupid cluttering references by scrawl and conversy

What a timewaster this github :( :( :(

[erwincoumans]

Created a new issue, hopefully without the "references this issue" clutter:
https://github.com/erwincoumans/bullet3/issues/26