I18n: Update translation ast (88%).

189 translated messages, 24 untranslated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation de (100%).

213 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation nb (100%).

213 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).