Fixed bug B65-ZK-1804: Calendar should not be able to select year less
than 1900 or greater than 2099
http://tracker.zkoss.org/browse/ZK-1804
Merge branch 'master' of https://github.com/zkoss/zk into B65-ZK-1804
add comment for B65-ZK-1804
Merge branch 'B65-ZK-1804' of git://github.com/RaymondChao/zk