Translate German comments in filerec.cxx and doxygen-ify.

Change-Id: Iebe05867395ca5674242b18038b53d5362869d07
Reviewed-on: https://gerrit.libreoffice.org/9956
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>