Better escaping of text passed into GFM
Created by: rspeicher
This was fairly tricky to deal with since gfm()
can't just escape the
text itself, since our custom Markdown parser converts Markdown to HTML
and then passes it to GFM, so that would make it useless. We can't
escape all text returned by GFM because then references wouldn't work.
Closes #1444 (closed)