Start work on DGS coverage. Refs #10611
rst file. refs #10611
A few properties and calculations. Refs #10611
More input processing. Refs #10611
Use intersections to update coverage. Refs #10611
Intersections with H planes. Refs #10611
Intersections with k and l planes. refs #10611
Test and documentation. Refs #10611
Fix doctest. Refs #10611
Merge branch 'feature/10611_DGS_coverage' into develop