SOON(module 8)

LIST OF CHANGES
-Added pictures for all pieces for the gui
-Commented out print board calls in Game and GameManager, will only use those for debugging now
-GameManager now checks for pawn promotion at the beginning of each turn, and I re-enabled check and mate
-Added ChessGameWindow which is the class behind the GUI, sends user input to a new class called 'GuiInterpreter'
-GuiInterpreter handles input from the GUI and sends it to the GameManager to modify the game state
-Not sure what was changed in Main, I think it may have just been me formatting