Changes

Summary

1. proper sorting of result (amending f458547b4f0f);
2. merged
3. enforce rebuild of Isabelle/ML;
4. more operations;
5. more specific vacuum operation, which is also relevant to PostgreSQL;
6. tuned signature: removed redundant argument;
7. tuned signature;
8. proper build_uuid for Build_Process.Task: thus old entries are removed via prepare_database/clean_build;
9. more informative Build_Process.Snapshot;
10. more explicit snapshot of "_state" and "_database";
11. tuned;
12. removed redundant State.workers: directly maintained within the database, using with SQL update;
13. more thorough cleanup;
14. tuned signature;
15. tuned signature;
16. tuned signature;
17. more thorough synchronization of internal "_state" vs. external "_database";
18. more database content; clarified signature;
19. clarified modules;
20. clarified signature;
21. clarified modules;
22. tuned output;
23. tuned output;
24. Adjusted to new map update priorities
25. bring priority in line with ordinary function update notation
26. merged
27. use tree (simpler) instead of rbt (exercise)