Use ConstraintDynamics in World
Some speed improvements in ConstraintDynamics
Set shape to NULL when no collision or visual tags are given
Corrected debug message for NULL shapes
modified balance app
Merge branch 'origin/master'

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