add release date
release 6.5.5
Bug fixed Sandbox portallayout case: the max, min and collapse button should work in tablet
update version to 6.5.6-FL
Merge branch '6.5' of https://github.com/zkoss/zk into fix-65
add case
fix zktest borderlayout case: change from set flex="true" in layout comp to set vflex="1" in layout's child comp