[ODE] Collision impact force

[Tyler Streeter]

> Tyler,
> 
> sounds like you've thought about this - what was wrong with "the joint feedback way" aren't the reaction mags easy enough to get hold of, too noisy, what gives - (?)
> 
> Bob.
> 

Actually, I haven't tried the joint feedback way.  I just happened to
try using the penetration depth first and never got around to using
the joint feedback structure.  If you do use the joint feedback to
adjust the sound volume, let me know how it goes.

Tyler