I18n: Update translation de (100%).

352 translated messages.

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

352 translated messages.

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

352 translated messages.

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