This implements legacy parser interface using XFastParser, and
unit test is also added.

Change-Id: Ia2eb7d517d80a3f7ec0cf26ffa2e5747ad22b186
Reviewed-on: https://gerrit.libreoffice.org/26229Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>