version 3.11.91
  - Work around non-existent Makefile during clean
  - Mark help images as untranslatable
    Delete translations of images that don't need them and of images that
    aren't used any more.
  - Review index and pref help for 3.12
  - Update intro and features help for 3.12
  - Post-release version bump to 3.11.91
  - Added/Updated Translations
    - be, courtesy of Yuri Matsuk
    - cs, courtesy of Marek Černocký
    - fr, courtesy of Alain Lojewski
    - hu, courtesy of Gabor Kelemen
  - Added/Updated Documentation
    - cs, courtesy of Marek Černocký
    - es, courtesy of Daniel Mustieles
    - hu, courtesy of Gabor Kelemen