This can be easier done by just removing the autojoin flag

The available options regarding closing tabs should be enough

Clearly separate join and creation even though this is not the case
protocol wise

There are no legacy accounts anymore

If disco_muc is called without callback, user_data is None.
If user_data is None, nbxmpp does not pass it as argument to the callback

- Update name in Roster
- Update name in MessageWindow
- Update name in GroupchatControl