- added mandatory reviewers JS logic Fixes: #4219
- added option to forbid author to be a reviewer via JS/Frontend checks. Fixes#5190
- added option to forbid adding new reviewers except those defined. Fixes#5208
- made compare and commit range pages more consistent with other commit diff pages
- removed mergerly, closes#4665. Old diff2way is replaced by new diffs with
side-by-side mode.
- cleanup button behaviour on compare page. Added help text and
generally improved UX
- switched file-diffs to compare page with file filter. Part of #4000
- added collapse/expand commits buttons in compare views.