MUC implementation: first draft /!\ the experimental muc branche of wokkel must be used - bridge: new roomJoined signal - wix: contact list widget is now in a separate file, and manage different kinds of presentation - wix: chat window now manage group chat (first draft, not working yet) - wix: constants are now in a separate class, so then can be accessible from everywhere - wix: new menu to join room (do nothing yet, except entering in a test room) - new plugin for xep 0045 (MUC), use wokkel experimental MUC branch - plugins: the profile is now given for get_handler, cause it can be used internally by a plugin (e.g.: xep-0045 plugin)