fix: remove obsolete German keys

Created by: Tirokk

Authored by Mogge Jan 21, 2020 Merged Jan 21, 2020

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🍰 Pullrequest

In order to have consistency between the two language files, I removed the obsolete German keys. Also fixes a minor spelling error.

Issues

• fixes #2528 (closed)

Todo

• Avoid obsolete keys in any language file