Linkify IRC channels

Make '#foo' in a message or buffer title clickable, taking the user to the IRC
channel specified, joining it if necessary.
Merge pull request #144 from lorenzhs/linkify

Linkify IRC channels
Add missing keyboard shortcuts on landing page
Fixes #80
IRC linky: don't match HTML encoded chars (&#41;, &gt;, etc.)
Merge pull request #153 from lorenzhs/fixirclinks

IRC linky: don't match HTML encoded chars (&#41;, &gt;, etc.)