OpenDocument Version 1.2 [1] requires that missing presentation:pause
attribute be treated as if 0 s duration was set.

Changing the default here in PresentationSettings ctor will (1) allow LO
to conform to the standard reading ODF; (2) not introduce the 10-s pause
when importing external formats (such as PPT, which has no pause, and
should work as if the pause is 0 s); and (3) change the default pause
value for the newly created presentation (if no template is used).

[1] http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html#__RefHeading__1417722_253892949

Change-Id: I6df2e83d07980b679574ec81fae001ca40f116fd
Reviewed-on: https://gerrit.libreoffice.org/68190Reviewed-by: Heiko Tietze <tietze.heiko@gmail.com>
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>