franky turns lua errors into asserts
franky adds function to obtain the screen width and height
franky unifies the get screen size funciton to return a table
franky adds a get position function to the actor class
franky allows the possibility to pass an object to the function being execute so that we have a global pointer to the actor that is currently calling the script
franky adds a get position function and calls the function with the actor owning the script component