Created GameOver class

This class represents the Game Over GUI, where the player can choose to
either start a new game or quit.

Basic layout set up, and functionality for buttons.
Updated GUI/Driver classes to allow custom window

*Updated GameDriver class and GUI classes to allow an input width/height

*Changed GUI classes to start with an input width/height

*Added GameOver GUI to GameDriver's logic of Game States (into, new
game, game, game over)