writerfilter: unused 'using' in rtftok

Change-Id: Ie28d898d490ff695143e9f09502fa10db092ccc7
writerfilter: unused 'using' in dmapper

Change-Id: Id6a8362872bb4602b840da388189fecc046dd97e
writerfilter: write out table::BorderLineStyle::NONE

Change-Id: Ifc9e42f12c8e3d6ae1f98396fddf5bd6adcf3ba1