A tic-tac-toe bot that can play tic-tac-toe with you when you have no friend. Has 3 difficulty levels:
level 0: purely random moves
level 1: can recognize a winning move and play the move, or block the winning move from you
level 2: unbeatable? (still not sure about this)
&start <level: 0 - 2> : start the game
&move <position: 1 - 9> : move
&show_board : show the current game again
