Changes

Summary

1. merged
2. cronjob: build release from repository snapshot;
3. more operations;
4. clarified file operations;
5. proper link;
6. explicit website directory;
7. proper path;
8. tuned messages;
9. clarified platform families vs. bundles;
10. more general operations;
11. website index for existing bundles;
12. tuned messages;
13. added option -p for platform families; actually accept option -r;
14. more formal Release_Info; more incremental treatment of additional builds (bundles, library); tuned;
15. replaced shell script by Isabelle/Scala;
16. tuned;
17. tuned whitespace;
18. clarified;
19. tuned;
20. tuned message;
21. more robust wrt. old versions that use clear-text properties (e.g. Timing in build_history_base);
22. tuned;
23. integrity test of build_history vs. build_history_base; misc tuning and clarification;
24. clarified log_subdir vs. log_filename; support for sequential and parallel task blocks (unnamed);
25. tuned;
26. tuned;
27. provide USER_HOME, such that symbolic Path.explode("~") can be used remotely;
28. tuned signature; copy_dir using *this* Isabelle_System: note that File.bash_path is already expanded, but no variables are used here;
29. clarified modules;
30. allow to exclude named tasks;
31. support for separate sub-system options, independent of main Isabelle options; tuned;
32. tuned;
33. tuned;
34. more cleanup;
35. separate ISABELLE_HOME_USER (with its etc/settings);