/**
  * Return items that have this project object as parent (first level only)
  * 
  * This function will order subitems by position and ID by default, but it 
  * can be overriden in subclasses
  * 
  * If $type is used ProjectObject type will be used
  *
  * @param void
  * @return array
  */
 function &getSubitems()
 {
     if ($this->subitems === false) {
         $this->subitems = ProjectObjects::findByParent($this, null, 'position, id');
     }
     // if
     return $this->subitems;
 }