Added in a better mechanism for checking mistakes, so that it checks the whole board before proceeding in order to prevent a cell that is wrongly flagged in a further position from affecting the cells before it. This is only to fix low delays causing unexpected results, and should not theoretically be needed at all. However, mistakes by the auto player happen and the method is very quick so it is not a problem in terms of speed but can help reliability. Also changed the play again command back to enter instead of alt + p, as sometimes the program may get stuck from clicking somewhere and not being able to play again.