core: Deferred in onMessage.

onMessage now use a deferred which is passed to MessageReceived trigger through the post_treat parameter. This can be used by plugins to add deferred in the callback chain.

src/plugins/plugin_exp_command_export.py

@@ -100,7 +100,7 @@ class CommandExport(object):
         except ValueError:
             pass
 
-    def MessageReceivedTrigger(self, message, profile):
+    def MessageReceivedTrigger(self, message, post_treat, profile):
         """ Check if source is linked and repeat message, else do nothing  """
         from_jid = jid.JID(message["from"])
         spawned_key = (from_jid.userhostJID(), profile)