Blender Git Loki

Fix stability issue and further make collisions inelastic

The repulse when colliding points are approaching was being scaled
incorrectly by the impulse, causing some undesired elasticity in the
collision. I imagine this was a workaround to avoid penetrations
because the collision responce was being calculated with respect to
the incorrect state, but this is no longer necessary now that that has
been fixed. (had missed this case in my previous elasticity commit)

Other than that, I have bary interpolated the static repulses to avoid a
nasty instability issue in some corner cases.