Hi!

IRC links in ox-html are currently broken. There exists a special 'irc'
content handler on the web, telling browsers to open an irc link in an
external irc client. The format for such links seems identical to org
(irc:irc.freenode.net/user).

Previously links such as:

[[irc:irc.freenode.net/test][Irc link]]

Would export to 

<a href="irc.freenode.net/test">Irc link</a>

in ox-html.

After this tiny patch, it exports to:

<a href="irc:irc.freenode.net/test">Irc link</a>

which tells browsers such as firefox to open links in irc clients.

Let me know if you find any issues!

-Jay