Get24: Changing scene & passing event

We're continuing working on the terrible event handlers that we got from Fractionauts since it's already in the middle of the way and we will have to reduce so much stuff to switch back. The event passing is functioning well. However, if I have time I would definitely dive back in and simplify the passing methods.

The graphics that handles the events are however great. It's nice, simple and clean to interact with. If we have more time to playtest with 4th graders I would consider adding more colors to the backgrounds and buttons so that it looks more childish. But sofar I'm satisfied with the interface we have.

Another issue that we ran into is the scene changing. This is also a division of the event handler issue that the state of the scene will not properly pass to the next scene. Additionally, when we switch out the pygame window and switch back, the handlers magically work again. Therefore we switched the type of the button so that detects the location of the click instead of handle the event that it passes.

We're definitely approaching the end of the development since we already have the model of the game done. We will soon create the numbers and operations button and implement the model to the scene.