Merge remote-tracking branch 'origin/feature/5151_remove_custominterfaces_dependencies'
Merge remote-tracking branch 'origin/feature/7392_workspacehelpers_unit_tests'
Refs #7700. Moving duplicate checks.

This is back to the contract estabilished by the vtkDataSetFactory, but
it still allows me to handle things at the right time. Putting a unit test
back as well.
Merge branch 'feature/7700_spf_remove_initialize' into develop