Split watcher messages at the correct length.

earwigbot/irc/watcher.py

@@ -122,4 +122,4 @@ class Watcher(IRCConnection):
             if chans and frontend and not frontend.is_stopped():
                 pretty = rc.prettify()
                 for chan in chans:
-                    frontend.say(chan, pretty[:500 - len(chan)])
+                    frontend.say(chan, pretty[:400])