[ticket/12937] Do not return false. Return null for get and array() for all.

PHPBB3-12937
Merge remote-tracking branch 'github-bantu/ticket/12937' into develop-ascraeus

* github-bantu/ticket/12937:
  [ticket/12937] Do not return false. Return null for get and array() for all.
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12937] Do not return false. Return null for get and array() for all.