Update added overlay to allow more easily modify the code.

[Aphexus]

def update(fen, game_board, overlay = None): check_for_quit() game_board.update_pieces(fen) if not overlay is None: overlay(game_board.display_surf) pygame.display.update() fps_clock.tick(FPS)

It would be nice if the board could be dynamically resized

maybe I will modify that later.