Concept of scene switching in Haruhi

Create a Scene class to allow switching and nesting scenes inside Haruhi. A Scene is a package of callbacks(mousemotion, refresh) that activates when a Scene is switched on. This means that you can create a Scene that would deactivate listening to any user input and show a movie. A Scene should have an activate function that would block using the event loop until its deactivate function is called. A Scene also needs to save the callback state of a previous scene if a previous scene is running, pause the scene and use its own callbacks. This enables easy switching between modes in a program while preserving event-orientedness.