Use ConstraintDynamics in World
Some speed improvements in ConstraintDynamics
Merge branch 'origin/master'

Conflicts:
	apps/balance/Controller.cpp
	apps/balance/Controller.h
	apps/balance/MyWindow.cpp
	src/dynamics/ConstraintDynamics.cpp
	src/dynamics/ConstraintDynamics.h
	src/dynamics/PointConstraint.cpp
	src/simulation/SimWindow.cpp
	src/simulation/World.cpp
	src/simulation/World.h