l10n: de.po: translate 44 new messages

Translate 44 new messages came from git.pot update in
c6bc7d4 (l10n: git.pot: v1.8.3 round 2 (44 new, 12 removed)).

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Acked-by: Thomas Rast <trast@inf.ethz.ch>