With this, SVM files are still written to ODF, but accompanied
by a replacement png graphic.

Change-Id: I2c949f100dd5197a10c741baa42ea740f3a1415a
Reviewed-on: https://gerrit.libreoffice.org/45567Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Armin Le Grand <Armin.Le.Grand@cib.de>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Reviewed-on: https://gerrit.libreoffice.org/45677Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>