A BAlert is used to inform the user of room invitations― InviteDialogue―
and to send their response directly to the protocol's looper.
Some new protocol messages were added (and older ones were moved around
to compenstate)― IM_ROOM_SEND_INVITE, IM_ROOM_INVITE_REFUSED,
IM_ROOM_INVITE_RECEIVED, IM_ROOM_INVITE_ACCEPT, and
IM_ROOM_INVITE_REFUSE.