othello.icn: Program to play the board game Othello (or Reversi)

Othello is a board game based on the older English game Reversi.
This program provides a computerized opponent for a human player.

To make a move, click on a square to place a piece.  The program
flips the appropriate pieces, cogitates a bit, and then makes
its own move.  If you have no legal move, click anywhere to pass.

Play ends when neither side can move; the player with the larger
number of of pieces is the winner.

Commands are issued by pressing a key:

N       new game
G       go (the program makes a move; to play white, start with this)
H       hints (toggle the display of legal moves)
Q       quit

U       undo last move (which is cheating, of course)
P       pass, even if not legal, changing the side to move

W       write game history to standard output
S       save current game to a file
O       open game from a file
        (or: pass a filename argument when starting the program)

1 to 9  set program lookahead depth (the default is 5)
E       display an evaluation of possible move choices
D       start demo mode; press space bar to end demo

In addition to the control commands and the click-to-move action,
selecting a square by right-clicking or control-clicking makes
a move in isolation without prompting a computer response.