Position based dynamics

Instead of working on a regular particle system, I tried to get one working which is based on the paper "position based dynamics" (PBD). With the help from Micky Kelager who wrote a paper on a bending constraint which can be used with PBD I was able to program a very nice smooth cloth application.  PBD is the way I'll go in the future when working on particle systems; it's fast and stable.