Introduced visitor that goes through Box2D World bodies.
Victims of refactoring.
Minor refactoring.
Minor refactoring.
Replaced iterators with body visitors.
Removed methods are needed no more.
Attached CGShape to Ground body's user data.

This was a cause of subtle bug. Each box2d body in the system is
guaranteed to have CGShape attached to userdata. However, ground body
did not have such user data. Set dummy user data.
Updated lua script template.
Auto updates.
Body visitor. Use to traverse to box2d world bodies.
Refactored interfaces. Removed the prefix, I.