[ticket/13226] Fix the usage of $rank_img

PHPBB3-13226
[ticket/13226] Add functional test for group ranks

PHPBB3-13226
[ticket/13230] Add missing globals and missing request object for path helper

PHPBB3-13230
Merge pull request #3079 from nickvergessen/ticket/13230

[ticket/13230] Add missing globals and missing request object for path helper
Merge remote-tracking branch 'github-nicofuma/ticket/13226' into prep-release-3.1.0

* github-nicofuma/ticket/13226:
  [ticket/13226] Add functional test for group ranks
  [ticket/13226] Fix the usage of $rank_img
Merge branch 'prep-release-3.1.0' into develop-ascraeus

* prep-release-3.1.0:
  [ticket/13230] Add missing globals and missing request object for path helper
  [ticket/13226] Add functional test for group ranks
  [ticket/13226] Fix the usage of $rank_img