Fix bug ZK-1577: vlayout default spacing missing when groupbox has hflex="1"
http://tracker.zkoss.org/browse/ZK-1577
Fix bug ZK-1535: Bug in ZK 6.5.1 :: Calendar component does not display the 6th week
http://tracker.zkoss.org/browse/ZK-1535
Merge remote-tracking branch 'VincentJian/B65-ZK-1577'