Remove the close() method and closed attribute. Remove all the calls to
close(). (Save one bool per XmlNode, yay, and save a few ifs and some
useless function calls. At best it should be unnoticeably faster and lighter
and save a few keystrokes in the future)
Instead of ignoring the stanza, we send back an error of type
remote-server-not-found each time it's possible.
Also avoid having to do if (!irc) return; everytime.
fix#3045