Added name fields to Collision Object and Shape.

Added name field to Typed Constraint.
Added accessor for gravity in dynamics world.

src/BulletDynamics/Dynamics/btSimpleDynamicsWorld.h

@@ -52,6 +52,8 @@ public:
 
 	virtual void	setGravity(const btVector3& gravity);
 
+	virtual btVector3 getGravity () const;
+
 	virtual void	addRigidBody(btRigidBody* body);
 
 	virtual void	removeRigidBody(btRigidBody* body);