Fix player 1 getting extra turn at end of game.

Fix a bug where player 1 would get an extra turn at the end of the
game due to an off-by-one-error. Also update the front-end to
match, so that the final turn still displays as, e.g., 1200/1200
instead of 1199/1200.

The bug can be observed most easily by starting a training game
with number-of-turns set to 1, and observing your own bot move
twice, but occurs in arena matches as well.