Summary
- merged
- proper build_selection for clean_build (amending 961285f581e6): e.g. relevant for "isabelle build_doc";
- clarified signature (again);
- clarified exclusion: operate on completed selection, as last step;
- tuned;
- tuned signature;
- clarifified selection: always wrt. build_graph structure; tuned signature;
- tuned;
- tuned signature;