[ODE] Triangle-box collider contribution

[Erwin de Vries]

> I don't see a compelling reason to abandon Erwin's current implementation
> just yet.  It won't make sense to replace his code until someone writes a
> frame-coherent collider that isn't vulnerable to missed collisions.

Although i've only briefly looked at the code (and havent seen visual
results), i would give the guys from that made the Serious Engine some
credit. They probably knew what they were doing, while my implementation is
mostly based on what i believed that might work. Its far from perfect and
has fundemental flaws in depth computation.

I agree a swept volume collider would be very good, and probably would be
the way to go, but until we have it we might take a look at the alternatives
available right now. When several people post their results, and if most of
them see improved behavior in their apps i think it would be wise to replace
my code with this one.

Erwin