move syntax highlighter code to separate file
initialize syntax highlighter with real classes and data attributes

This makes the classes used for highlighting match up with the HTML5
recommendations, and removes the use of the ugly braced config stuffed
into the class attribute.  It also opens up the option of the pod->html
converter providing syntax highlighting configuration in a reasonable
format.
use normal pre styles for syntax highlighter

Instead of applying styles to syntax highlighter blocks and trying to
match verbatim sections to that, just use the normal <pre> styles.  This
simplifies the rules needed, and removes the need to extend the syntax
highlighter's css rules.