Draft: Still something funky in collisions :O

I am pretty sure that collision forces and jacobians are being computed correctly. Now I suspect that the forces computed at the collision particle simulation object are not being mapped correctly to the actual degrees of freedom. In the simulation render I see the correct force vectors but the endoscope does not react accordingly, in particular when dealing with high stiffness collisions.

I fixed a small bug in the applyJ in MappingInfo<Particle3DTag, SphereCloud>, but it is not enough to correct the behavior. Maybe having multiple mappings is something we have to debug??