added constants for magic numbers and comments for GameOverScreen
added constants for magic numbers and comments for GameOverScreen

PinPinx/TD_Game_Engine,brandonnchoii/VOOGASalad,jeremydanielfox/game_engine,keikumata/CS308_Tower_Defense,ninasun/game_engine,keikumata/CS308_Tower_Defense,ninasun/game_engine,jeremydanielfox/game_engine,PinPinx/TD_Game_Engine,Jgilhuly/VoogaSalad,brandonnchoii/VOOGASalad,Jgilhuly/VoogaSalad