Merge pull request #850 from dgough/next

Changed ScriptController so you can execute a lua function that is in a table
Added a lua function "convert" to convert a userdata value to another gameplay class type.
The purpose of this function is convert a Control to a Button, or PhysicsCollisionObject to a PhysicsRigidBody.
This function will change the meta table of the userdata value to the meta table of the class with the given name.