Added move with comments logic

[esdudnik]

Hello! I've needed an ability to add comments per Move. I've added a new method MoveWithComments that is actually does everything that was done by Move and adds a new entry to Game.Comments. The Move calls now the MoveWithComments with an empty comment. In the decodePGN I've change the call for Move to MoveWithComments. Thanks a lot for a great library!