Feature ZSS-576: Support Excel "Protect Sheet" allowed actions
1. Check button and menu should be disabled when protect
2. Check protection on action handler
3. Handle focus and selection when protect
4. Test cases
Merge branch '3.5' of https://github.com/zkoss/zkspreadsheet into ZSS-576
Merge pull request #1 from RaymondChao/ZSS-576

Feature ZSS-576: Support Excel "Protect Sheet" allowed actions