Instead of passing around pointers to the Server, Server::Get() returns
the server's pointer (simplifying some things a good bit).
As a result, headers have been cleaned up, and some redundant KeyMaps
have been placed in Maps.h.
This window (Chat→Room directory) is to be used for either a list of
publicly available rooms (in most protocols), or for a list of
joined-but-hidden rooms (as it'll used with libpurple, to list its
ChatBuddies).
Each room is sent individually from protocols using IM_ROOM_DIRECTORY
messages sent in response to a IM_GET_ROOM_DIRECTORY message.