This should be the full system path to the location of the Smarty
class files. If this is not defined, then Smarty will attempt to
determine the appropriate value automatically. If defined, the path
must end with a slash.
Example 11-1. SMARTY_DIR
// set path to Smarty directory
define("SMARTY_DIR","/usr/local/lib/php/Smarty/");
require_once(SMARTY_DIR."Smarty.class.php");