- Extract local KEY_CODES to static variable
- Guard clause to prevent try render a null scene
- Add Keyboard.js to load
- Add Keyboard module and tests to Keyboard.pressed_keys
- Add a preload queue in Core class
- Add SceneException class
- Add a test bg image
- Add SceneException to load
- Add SceneException to load and some engine tests
- Add setChildIndex method to Scene class