l10n: de.po: use imperative form for command options

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
l10n: de.po: Fixup one translation

English grammar with German words doesn't make it a German translation. ;)

Signed-off-by: Stefan Beller <stefanbeller@gmail.com>
Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
l10n: de.po: translate 62 new messages

Translate 62 new messages came from git.pot update in 16742b0
(l10n: git.pot: proposed updates for v2.2.0 (+62)).

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>