ftnfrm: Translated comments from German to English

Change-Id: Ib856322746efbb6e95ec899eaad93e63832c65ce
Reviewed-on: https://gerrit.libreoffice.org/8948
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>