plugins (games): more factorization and flexibility for launching and joining games: - "MUC user joined", "MUC user left" and class XMPPHandler are managed directly in RoomGame - renamed __init__ parameters 'player_init_data' to 'player_init' and 'options' to 'game_init' - pass the players list in radiocol method 'createGame' and signal 'radiocolStarted' (needed for invitation system and for UI players identification) - added some parameters to manage who can invite, who can join, who to wait for... managed with check***Auth methods - joining a game that is already launched may be possible, regarding these parameters and the invitation list - leave and join a game again is partly managed: new tarot round is launched, we should keep playing the same round instead