auto generate side nav bar
fix duplicate links and add a warning against duplicate headings
correct link - should be to correct section since there are multiple entries on each page
refactor usage a little more
add a few more languages to code blocks
fix the highlighting (pending pull request on marked-extras)
Fix footer, remove un-neeeded js
upgrade bootstrap
remove hard-coded assets and use cdns where possible
avoid the holder.js 404 by moving the src to data-src for holder.js references