remove the bridge-speaker from the message when relevant

this allows downstream event handlers to react to e.g.:

<discord_user> !weather 12345

as if they were normal leading IRC commands

ircbot/bot.py

@@ -162,6 +162,7 @@ class DrReactor(irc.client.Reactor):
                     if sender_nick == channel.discord_bridge:
                         short_what = ' '.join(what.split(' ')[1:])
                         match = re.match(addressed_pattern, short_what, re.IGNORECASE)
+                        event.arguments[0] = short_what
                     else:
                         match = re.match(addressed_pattern, what, re.IGNORECASE)
                 except IrcChannel.DoesNotExist: