By kiam: Added the code to allow third-party modules to indicate to the module where to look for the highlighter recipes; re-arranged the code.
By kiam: added the code to handle the CSS files, to allow third-party modules to alter the path to the plugin (and change it to an external URL); removed some JavaScript settings not anymore used.
By kiam: Changed the name of a public function.
By kiam: Removed the reference to the undefined PHP variable; re-arranged the code.
By kiam: Removed the reference to the undefined PHP variable; added the code to handle the CSS files; added the code
to allow third-party modules to alter the path where the jQuery plugin is found; added the code to allow third-party to
alter the list of recipes and CSS files; changed the code to depend on the Variables API module.
The latest developed code requires a version of Variables API module that is still without an official release. Do not use the development snapshot of this module if not for testing, and in any cases don't use it in a production site.