EPUB export: allow setting a custom version

By parsing the FilterData key of the media descriptor, similar to how
the PDF export does it.

The default is still EPUB3, but this now exposes the ability of
libepubgen to emit EPUB2 if wanted.

Change-Id: I23834fa28db9b01ef4cce4a142331b1cc9ecb3c2
Reviewed-on: https://gerrit.libreoffice.org/41566
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

0 files changed, 0 insertions, 0 deletions