Changes

Summary

1. merged
2. more informative known_files: known_theories within the local session directory come first; more thorough Session.Base.platform_path;
3. less global theories -- conflict with AFP entries;
4. support for known theories files (according to multiple uses);
5. proper display_name;
6. clarified theory_long_name (for qualified access to Thy_Info) vs. short theory_name (which is unique within any given theory context);
7. tuned signature;
8. proper import qualifier for global theories; clarified uniqueness;
9. explicit theory qualifier for session "HOL-Proofs": its theory name space overlaps with session "HOL", even for further imports;
10. proper qualifier for imports;
11. clarified, according to Scala version;
12. tuned text;
13. clarified signature;
14. NEWS;
15. more robust: user could provide name with "/" etc.;
16. clarified main ZF.thy / ZFC.thy, and avoid name clash with global HOL/Main.thy;
17. added system option record_proofs, which allows to build HOL-Proofs without special Proofs.thy;
18. clarified main CTT.thy, and avoid name clash with global HOL/Main.thy;
19. tuned signature -- prefer qualified names;
20. more qualifier treatment, but in the end it is still ignored;
21. tuned signature;
22. provide Resources.import_name in ML, similar to Scala version; reset default_qualifier for now; tuned;
23. clarified;
24. more session_base information in ML; tuned signature;
25. more operations;
26. tuned signature;