[ODE] patch - position-correcting constraints

[Adam D. Moss]

Adam D. Moss wrote:
> This EXPERIMENTAL patch attempts to resolve penetrations by
> altering body positions and orientations instead of altering
> their velocities.
> 
> This has the effect of almost entirely eliminating the fake-
> bounce and explosions caused by interpenetrating geoms.

I don't know if my patches are reaching the list or if
anyone cares.  An historically recurring problem on the
ODE list. :)

--Adam