GUI

[grf14003]

Add GUI functionality to human player mode. This will allow the human player to use the GUI to communicate with the AI without any need for a server. The player should be able to click on a piece and a spot to move it to. If it is a valid move, the AI makes the next move. If it is an invalid move, the player must choose a different move.

The GUI should be implemented on top of the current board class. It doesn't have to implement any of the board logic because all of the logic is provided in the Board API. All it has to do is draw the board state each time a move is made, and allow the user to select moves while testing for their validity.

Nate, I see you reimplemented a lot of the logic in the Board class inside this new GUI.py file. This is okay for now, but eventually we want to get the GUI to use the Board object because we know that logic is verified to be working.