Hi Nicolas,

> The proper fix would be to patch "org-irc.el" and add an export function
> there. "irc" links are not default links in Org, so there is no reason
> to hard-code them in "ox-html.el".

Thanks for pointing that out! I didn't even realize up until now org had
support for custom link types.

I've attached a second patch which adds a new function to org-irc.el,
which seems to handle export of irc links in ox-md and ox-html
properly. I'm very new to this system, so please make sure it's correct,
and I'll be happy to follow up with corrections if it isn't!

Because I added support for md links in org-irc.el, I also removed the
workaround I added a while back for that in ox-md.el.

-Jay