ScJumpMatrixToken unconditionally deletes the ScJumpMatrix pointer it
receives. But it's copy constructor also just copies that pointer,
meaning that we could end up freeing that pointer twice.

ScJumpMatrix has no copy constructor, so I just managed it via
shared_ptr.

Change-Id: I9cf13312afb4f2869fdc878e5f34060614e31842
Reviewed-on: https://gerrit.libreoffice.org/41728Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Noel Grandin <noel.grandin@collabora.co.uk>