Changed any phptemplate_HOOK functions to zen_HOOK, since phptemplate_HOOK is nonsense with sub-themes.

Modified the help text to be more succinct and easier to understand.  Modified the breadcrumb to be a double colon because the long arrow looks awkward.  Changed the _phptemplate_variables to be a semi-useful example instead of a giant block that is commented out.  I am still uncomfortable with this file as it went from a very tiny file to an extremely verbose one. I'm recommending trimming it even more, if not just providing a link to an example template.php file posted on drupal.org with more thorough documentation.

significantly improved template.php, with lots of documention, comments, and some simple examples of useful theming tricks

See #81217 for more.