Developments:
-Game structure is complete
-Correctly ends and does not lag anymore
-GridWorld messaging is fixed
-Documentation has been added

To-do:
-Add correct menus and buttons for Checker game functions (i.e. new
game)
-Change GridWorld window title to Checkers
-Add piece displays
-Implement networking
-Finish AI bot
-Implement start-of-game options (i.e. Choose network, CPU, or human
opponent)
-Create NetworkPlayer class (tentative for now)