Set the framerate of the renderer.
Notice that if a computer couldn't render as fast as specified in the
framerate, game will proceeed slowly, so don't use a framerate too high for
the target device.
A good framerate for a mid-level computer is 20~60 FPS (in an average
game), a good framerate for a mobile device is 15~30 FPS.
fps - The framerate in frames/second.
GameEngine.Renderer.setFramerate(20);