MUC Room Roster broken after Strophe Reconnect

[bhelm]

i Implented a reconnect feature and noticed that the roster is broken for newly joined rooms after the reconnect. i fixed it by setting

xmpp.muc._muc_handler = null;

after the disconnect / before the reconnect.
i guess its because the join method does check if the _muc_handler is defined and defines it if not, and it needs to be redefined after the reconnect.

please refactor to make it work after xmpp.disconnect() and xmpp.connect() again.

let me know if you need more explaination.