public static function loadClass($classname, $loadscheme='Web2All', $package='', $set_includedir=false) {
    $class_exists=class_exists($classname) || interface_exists($classname);
    if ($class_exists && !$set_includedir) {
      // if class already exists, we don't need to do a thing
      // but one CAVEAT: if the class was loaded with $set_includedir==false and now the $set_includedir==true
      // then we do not add the path to the include path. 
      return;
    }
    
    self::includeClass($classname, $loadscheme, $package, $set_includedir);
  }