[ODE] Velocity clamping

[Matthew Harmon]

Hi all:

I want to put a "reality check" in for body velocities and was wondering if
anybody has done this or can recommend the best/fastest spot to do the
check.

Sometimes, on rare occasions, we will get a collision (or set of them) that
throws a body off into #NAN land and that obviously causes problems
downstream in ODE.  (Traps in Terrain collider, etc.)

I know I really shouldn't be doing it this way, but because we may be
running ODE faster than our own "update" code, I'd like to put this
check/clamp directly into ODE to cut down on overhead.  That way, the next
time we hit our own update code we can deal with the situation "properly"
before it has gotten out of hand.

Any suggestions would be most appreciated.