Message and message_correct::Replace now has typed Id

xmpp/ChangeLog

@@ -13,6 +13,8 @@ XXXX-YY-ZZ [ RELEASER <admin@localhost> ]
         use RoomNick as sender nickname; previously RoomNick was an alias for String
         now it's a newtype wrapper around ResourcePart (!485)
       - Agent::send_room_private_message now takes RoomPrivateMessageSettings (!487)
+      - Event now exposes Option<MessageId> for incoming messages, and MessageId
+        for incoming message corrections; type alias Id has been removed (!504)
     * Added:
       - Agent::send_room_message takes RoomMessageSettings argument (!483)
       - Agent::send_raw_message takes RawMessageSettings for any message type (!487)