import part for: "export to extension namespace instead of odf ..."

See master commit a4e4cdcdd7acfe779b2a3b244dd449f136308a93

(cherry picked from commit 40ac1ada98e3e2648daf9d17e520040be2c17911)
Signed-off-by: Michael Stahl <mstahl@redhat.com>

Conflicts:
	xmloff/source/style/PageMasterStyleMap.cxx

Change-Id: I0b61e05e3b153ba7efe351b18cb705ea6348f546
(cherry picked from commit 55568c0b95d2b2a072b896107963052bf78f1ff0)
Reviewed-on: https://gerrit.libreoffice.org/13391
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>