When only "not joined" message is delivered, be more helpful

As suggested in #3

Check if someone is in the room before saying the join

It seems GTalk repeatedly sends presence to the room, even when
already joined, which was causing many extra messages.

Closes #4

Better error recovery when connection goes down

Use BasicPrelude, reformat import list

Fix many warnings

hlint

Command to list bookmarked rooms

Bookmark every room we join

Join/leave messages

Show participants on join

Dedup the who list

Improvements to the copy

Command to list room participants

Join password-protected room by invitation

Add owners to members only rooms during invite

Create rooms as members-only

Send "failed to join" message on MUC join error of any kind

Fix room leaving

Better part message

Pick a random conference server