core: sendMessage triggers now use a treatments deferred;

- treaments deferred can be used by plugins to change XML elements before sending them, in a similar way as for newMessage
    - sendMessageXml trigger became useless, so it as been removed in favor of the new deferred

src/core/xmpp.py

@@ -112,7 +112,7 @@ class SatMessageProtocol(xmppim.MessageProtocol):
 
     def onMessage(self, message):
         debug(_(u"got message from: %s"), message["from"])
-        post_treat = defer.Deferred() # XXX: plugin can add there treatments to this deferred
+        post_treat = defer.Deferred() # XXX: plugin can add their treatments to this deferred
 
         if not self.host.trigger.point("MessageReceived", message, post_treat, profile=self.parent.profile):
             return