4.15.2

- Add small delay before reloading menu tree (!6)
- Clear entry's error icon and tooltip
- Update copyright year
- GitLab is the new bugtracker
- Remove unnecessary code for unsupported glib versions
- Remove padding from context menu
- Fix memory leaks when sorting items
- Update README.md
- Apply light blue to 16px icon
- Improved and simplified icons for better scaling
- Add back git tag
- Remove extra spaces in configure.ac.in so xfce-do-release works as
  expected
- Translation Updates:
  Belarusian, Czech, Hindi, Indonesian, Slovak, Swedish, Thai