added option for modp groups to use in a negotiation

 * partly rewrote join_room because it was hard to read
 * Correctly handle invites from anonymous rooms. Fixes #4057
 * Use HIG dialog for invitation requests
 * Fix bug where minimized groupchats where hidden after a reconnect
 * Removed some duplicated code

in 2 seconds.

shortcut to the uninstaller.

bored, so I did his job :).

I'm not sure how fatal if would be if the idle queue of NS lookups
hangs, but this fix won't hurt anyway, so I better fix it.

very very sure and gave that a few days of testing.

This is, however, only a half fix as this fixes that it fails when
there's None in waiting_descriptors[2], but actually, there never
should be None, so I have to investigate why there was none.

This patch is, however, correct and needed and the other queues also
have that check. It's just that I also need to fix the reason for
the None in the queue.

An idea: Currently, we don't send the message when the key has not
enough trust. How about showing the unauthenticated icon then, but
sending the message?

dbus-monitor actually showed the traceback that wouldn't appear
anywhere else.

Note to others: DBus.String needs to be converted using str()!

problem. Same here, remove check to notexistant once we have fallback
to disco.

This workaround will still work once fallback to disco is supported,
though it SHOULD be removed then as it's not necassary anymore then.

@bct: Now we only need to get rid of that password dialog :).