l10n: de.po: update German translation

Translate 96 new messages came from git.pot update in dfc182b1 (l10n:
git.pot: v2.13.0 round 1 (96 new, 37 removed)).
Signed-off-by: NRalf Thielow <ralf.thielow@gmail.com>
Acked-by: NMatthias Rüster <matthias.ruester@gmail.com>