German translations
Mix of manual and machine translations, should mostly cover everything, but might need some fixing/second opinions here and tehre.
Never done integration of QT translations, so might be missing some stuff there, but feel free to add those
Thanks for your PR More files need to be changed/added, for reference have a look at chinese language addition: https://github.com/fougue/mayo/commit/30f151fe1c366b28d849a6853d8096e06994776a
If you don't have time to make needed changes, then let me know. In such case I will close this PR, take your mayo_de.ts file and incorporate it myself.
I'm not to familiar with the qt translations so I'd appreciate if you'd finish it up I assume the qt translation files are added by qt itself, if there are any more translations needed lmk