/**
  * @param $array_of_names Create stack from array of names
  **/
 function __construct($array_of_names = Null)
 {
     // setup config:
     global $msConfiguration;
     self::$root_category_name = $msConfiguration['root-category-name'];
     if ($array_of_names) {
         $this->from_string_array($array_of_names);
     } else {
         $this->clean();
     }
     // will initialize the stack somewhat (add root)
 }