de: update POT file against current source
Created by: tijuca
Rebasing the curent KiCad upstream tree against the German PO file. Translate alle the new strings inside kicad.po, also removing all old and no longer used strings. Trying to fixup some more typo and grammer things.
The translation is surly improvable and doesn't enforce the claim to be complete. Please fixup bad translations!
This PR is a preparation for the GSIK translation into German.