PROPER SYNC FOR LATE JOINING CLIENTS!. This is a pretty big deal, as if this could not be made to work, it would be impossible to use physics at all. Since it appears that none of the physics engines are determisistic. In order to get this to sync properly, we need to reset the physics world for existing clients when a new one joins, so they both create the dynamics world with the same initial positions. This has to be done very carefully. It appears to work, but needs a lot of testing