Added IRC Notices. (errbotio#984)

* Added IRC Notices.

They are forwarded as normal messages (public or private) with an
extra['notice'] == True if they were notices.

* style

errbot/backends/irc.py

@@ -384,8 +384,8 @@ def on_welcome(self, _, e):
         t.setDaemon(True)
         t.start()
 
-    def on_pubmsg(self, _, e):
-        msg = Message(e.arguments[0])
+    def _pubmsg(self, e, notice=False):
+        msg = Message(e.arguments[0], extras={'notice': notice})
         room_name = e.target
         if room_name[0] != '#' and room_name[0] != '$':
             raise Exception('[%s] is not a room' % room_name)
@@ -402,12 +402,24 @@ def on_pubmsg(self, _, e):
             mentions = [self.bot.build_identifier(mention) for mention in mentions]
             self.bot.callback_mention(msg, mentions)
 
-    def on_privmsg(self, _, e):
-        msg = Message(e.arguments[0])
+    def _privmsg(self, e, notice=False):
+        msg = Message(e.arguments[0], extras={'notice': notice})
         msg.frm = IRCPerson(e.source)
         msg.to = IRCPerson(e.target)
         self.bot.callback_message(msg)
 
+    def on_pubmsg(self, _, e):
+        self._pubmsg(e)
+
+    def on_privmsg(self, _, e):
+        self._privmsg(e)
+
+    def on_pubnotice(self, _, e):
+        self._pubmsg(e, True)
+
+    def on_privnotice(self, _, e):
+        self._privmsg(e, True)
+
     def on_kick(self, _, e):
         if not self._reconnect_on_kick:
             log.info("RECONNECT_ON_KICK is 0 or None, won't try to reconnect")