Fixed footnotes in a post.
added blank "nil" layout for XML feeds.
added rss.xml per David Coyle
Switch to google code prettify highlighting

I prefer to keep my code in markdown vs liquid syntax, though it will be
painful at first.
Switch default liquid highlighter to rouge

Shouldn't use this, but in case I ever do, I want it to not depend on
python.
Updated code formatting on some posts.