express: Add window callback for user mode set

Wait for user mode set until we create channels in the window, this
way we are sure that 1) connected 2) user verified 3) we can chat in
channels....

src/bin/window.c

@@ -236,12 +236,12 @@ _cb_idle(void *data EINA_UNUSED)
         cbs.join = _callback_user_join;
         cbs.priv_msg = _callback_user_private;
         cbs.nick = _callback_user_nick;
+        cbs.user_mode = _callback_user_mode;
 
         /* TODO: Implement remaining callbacks
          * 
          * NB: See src/lib/Express.h for callback comments */
         /* cbs.mode = ; */
-        /* cbs.user_mode = ; */
         /* cbs.kick = ; */
         /* cbs.invite = ; */
         /* cbs.numeric = ; */