Bug fixed 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
Add comments about Bug B65-ZK-1793
add function isOutOfRange since 6.5.3
Parameterize year scope
Add function setMinYear_, setMaxYear_ to Calendar.js
Refine variable declaration