Started API Version

Added preupdate and postupdate method stubs to the Window class for extensibility as an API, plus a run function that performs setup and running of the world to further the API goal. Users can create classes that inherit Window, then add something like

    def preupdate(self, dt):
        #domethodstuff

to have new code run at the start or end of a frame update. This could be extended to other items like event handlers.