Private games #354
Description
Private games, and you can invite people to join.
There should be an optional parameter when creating a game to make the game private.
Private games mean no one can join directly.
If the game is private, the join button is replaced by a Select Button that allows to select a user from the server and invite him. Once invited he is automatically added to the player list, but his not ready yet. (like if he clicked the "join game" button).
He can still leave afterwards.
Only people who are already in the game can invite other people, the button doesn't do anything for anyone not in the game.