histogram: Implement graticule

[norihiro]

This PR implements

• [x] histogram: Implement vertical graticule
• [x] histogram: Implement fixed level mode
  • [x] The modified callback is annoying when changing numbers. It should be removed.
• [x] histogram: Implement horizontal graticule
  • Add disable option
• [x] histogram: Use 32-bit integer to accumulate pixels

• [ ] The commit is reviewed by yourself.
• [ ] The code is tested.
• [ ] Document is up to date or not necessary to be changed.
• [ ] The commit is compatible with repository's license.

Close #53

[norihiro]

When changing Top level, the modified callback frequently returns true so that typing is interrupted, which is annoying. I will remove modified callback. Instead, Graticule (Horizontal) will provide all selections from the beginning.

[norihiro]

The fix in the UI is cherry-picked to main branch.