Create simple constraints for circle physics

[justgook]

Objects with constraints should not be involved in main physics calculation, they should really only on master node (maybe)

• Offset fixed x,y offset of master center
• Distance - keep constant distance from master
• Range - keep distance in range of master, when passing middle of range, each next frame try to reduce distance by half ( need have minimal step size, for threshold)

Would be really useful for multi part bosses, where head moves as master, and multiple parts follow it as snake..