* po: use a single translation domain The desktop file and metainfo were translated from po/extra, but po/POTFILES also listed them, so translators often translated those strings in the main domain where they were never used. Spanish, Croatian, and Italian store listings and launcher entries shipped untranslated as a result. Drop po/extra and translate everything from po/. Translations that only existed in po/extra (French, Georgian, Russian) are folded into the main .po files first; where the two disagreed, the version that was actually shipping is kept. * po: prefer newer translations when merging domains