Show shortened room jid if possible on invite

src/xmpp/xmpp.h

@@ -83,6 +83,7 @@ void jabber_disconnect(void);
 void jabber_shutdown(void);
 void jabber_process_events(void);
 const char * jabber_get_jid(void);
+const char * jabber_get_domain(void);
 jabber_conn_status_t jabber_get_connection_status(void);
 char * jabber_get_presence_message(void);
 void jabber_set_autoping(int seconds);