Fix CopyAdvisorUtil.copy2 to copy IsRelatedTo-statements left out before

This implementation works so that it copies any IsRelatedTo statements
where both the subject and object have been copied during the normal
(old) copy process. The statements are marked as pending during the copy
and post-processed after everything else has been copied.

gitlab #607

Change-Id: I9170a448c127e0c7de6eae4260db5799ad7644bb