This is very useful functionality, this way it can be invoked from the
debugger and/or nested into an outer xml dump (sw/sd doc model dump)
more easily.

Change-Id: If6c83b11d0f3e65fcce71e8d820c6bc354f64d68
Reviewed-on: https://gerrit.libreoffice.org/65834Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins