update version to 6.0.6
Fix Bug B60-ZK-1784: client rod with hflex cause js error
update release-note
Bug fixed B60-ZK-1916: Different language codes for IE10 under Windows 8
http://tracker.zkoss.org/browse/ZK-1916
Bug fixed ZK-2247: nested iframe reloading content when detached parent window
http://tracker.zkoss.org/browse/ZK-2247