Box2D 2.3.0 MOAIBox2DMotorJoint example

This provides a new standalone sample under samples/physics/physics-box2d-motorJoint that demonstrates the new Box2D 2.3.0 'motor joint' at work. Run the sample, then click anywhere on screen. The body will be moved to where you click, and Box2D will use the defined motorJoint to return the body to it's initial position over time, with all the normal Box2D friction, mass, and collisions at work.