[ticket/11962] Resize posted images to fit and give them a class

PHPBB3-11962
Merge remote-tracking branch 'vsephpbb/ticket/11962' into develop-ascraeus

* vsephpbb/ticket/11962:
  [ticket/11962] Resize posted images to fit and give them a class
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/11962] Resize posted images to fit and give them a class