rollbot: no need to wait for MUCs If a user sends groupchat message to a room while the bot is still in the process of joining that room, the message will not be handled. And it shouldn't be, because the bot is not there yet! So there's no point in blocking the current thread on joining MUCs. Additionally, using wait=True triggers a warning: "Use of send mask waiters is deprecated." (from XMLStream.send)