if the key was duplicated from the reference language BUT not really
translated yet.
git-svn-id: http://piwigo.org/svn/branches/2.0@4644 68402e56-0260-453c-a942-63ccdbb3a9ee
fallback language. If the language file is missing, we tell it explicitely.
git-svn-id: http://piwigo.org/svn/branches/2.0@4638 68402e56-0260-453c-a942-63ccdbb3a9ee