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/plugins/plugin_misc_text_commands.py

@@ -42,7 +42,7 @@ class TextCommands(object):
         self.host = host
         host.trigger.add("sendMessage", self.sendMessageTrigger)
 
-    def sendMessageTrigger(self, mess_data, profile):
+    def sendMessageTrigger(self, mess_data, treatments, profile):
         """ Check text commands in message, and react consequently """
         msg = mess_data["message"]
         if msg: