static public GameObject AddChild (GameObject parent, GameObject prefab)
{
GameObject go = GameObject.Instantiate(prefab) as GameObject;
if (go != null && parent != null)
{
Transform t = go.transform;
t.parent = parent.transform;
t.localPosition = Vector3.zero;
t.localRotation = Quaternion.identity;
t.localScale = Vector3.one;
go.layer = parent.layer;
}
return go;
}