Small fix for plugins that accept non-channel messages

There's a long explanation in the code of this commit that says this:

> TL;DR OF THE BELOW: if the first parameter looks like a channel in
> addition to message type, then filter by channel. Otherwise, don't
> filter by channel.
>
> Here's the issue: plugins are *usually* multiplexed by channel. But
> that's only for messages that target channels, such as PRIVMSG and JOIN.
> For non-channel messages, such as server status messages (such as 001 on
> connect, or 372 for MOTD, etc) we want to ignore the channel aspect of
> plugin multiplexing. In order to accomplish this, we just check if the
> first parameter looks like a channel - i.e., starts with an octothorpe #.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

omnibot/plugin.py

@@ -58,6 +58,9 @@ class Plugin:
 
     def send_to(self, conn: IrcProtocol, who: str, message: str):
         message = Message(None, None, "PRIVMSG", who, message[:1024])
+        self.send_message(conn, message)
+
+    def send_message(self, conn: IrcProtocol, message: Message):
         conn.send(str(message))
 
     async def on_join(self, conn: IrcProtocol, channel: str, who: Prefix):