yaranullin/game/load_and_save.py: use event_system.post()
yaranullin/game/load_and_save.py: use event_system.post()

 load_board_from_tmx()
 * if called with in_place=True, return a Board object;
   if called with in_place=False, post 'game-request-board-new' and
   'game-request-pawn-new';
 * refactoring;
 * use ParseError(SyntaxError) exception.

ciappi/Yaranullin