This as a side effect also implements support for DOCX <w:pgNumType
w:fmt="lowerRoman" .../>.

Change-Id: Ifb524b25236a8bc774690266a4fa205154204109
Reviewed-on: https://gerrit.libreoffice.org/24273Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>