Add formatting for RPL_HELPSTART/RPL_HELPTXT/RPL_ENDOFHELP/ERR_HELPNOTFOUND

[progval]

For example with the reply to /help mode on InspIRCd:

Before:

After:

[genius3000]

Totally untested and I might be missing a reason but I would think Message::Server would be more suited for these instead of Message::Error. By default I think both direct to the status buffer, but each can be redirected in the client settings.

[progval]

Oh yes, of course, my mistake. I also forgot to implement ERR_HELPNOTFOUND and added it just now.

[progval]

ping?