[ODE] Found my LCP solver replacement bug

[David Whittaker]

infinity * 0 = nan

Doh!

That comes up when you have a "grazing" contact (i.e. 0 normal force),
dContactApprox1, and infinite friction all at once.  I don't think that
dContactApprox1 and mu = infinity really make any sense together... but
the LCP source said infinity * 0 = 0 for this case, so I followed that
convention.

Now that the auto-disabling code is in there, it's pointing out the jitter
I thought I got rid of... or maybe I moved something around that needed to
stay.  Grrrr.  I'll commit to CVS tomorrow night whether or not I get the
jitter fixed.

David