Mark unused parameters, and remove unnecessary widgets passed to callbacks.
Remove unused purple_roomlist_[gs]et_protocol_data.
Remove unused list of PurpleRoomLists.
Inline update_roomlist using GObject macros.
Remove use of PurpleRoomListUiOps->destroy.

  This can be achieved through object destruction notifiers.

  I'm not sure how the room list would ever get destroyed in Finch though, as the

  widget seems to hold a ref to it, which is cleared when the list is destroyed.

  But the list can't be destroyed until said ref is dropped.
Replace PurpleRoomlistUiOps->in_progress with notify signals.

Compile only. Might have done some tests, but I wrote this a while back and don't remember.