[ODE] Boxes floating in a plane

[gl]

> I agree.  I think that a solution that doesn't actually add momentum
> would be far superior, as in the provided patch.  Haven't had the need
> nor free time to test it out though.

I'm going to harp on about my original ideal of simply clearing the 
penetration correcting forces each step, so that once it's resolved, there 
is no leftover momentum.

On the surface this seems to give you the best of both worlds.  Now if 
someone with time and/or deeper physics experience than little me wants to 
try this/comment...
--
gl