Refs #7429. First cut at turning 4D back on.
Refs #7429. Don't put timestep stuff in XML as this causes issues.
Refs #7429. Removing debugging.
Refs #7429. Lifting restrictions on 4D data.
Refs #7429. Fixing unit test for 4D data.
Merge branch 'feature/7429_splatterplot_4D_data' into develop