Add uploaded files referenced from the site

This includes

 * everything from /t/uploads (minus some duplicates)
 * everything from /img/xchat
 * PDF files plus pharkas-vim from /guides
Convert absolute to relative links

This converts every link to 'http://cplug.org/' to a link to '/'. Many
of these are to files, but some are to pages. Also, formatting cleanup.
Merge branch 'files'