Changes

Summary

1. merged
2. prefer local timezone;
3. support for Isabelle/Jenkins log file format;
4. tuned;
5. clarified meta info;
6. tuned comment;
7. tuned signature;
8. tuned signature;
9. more permissive: accept all historic isatest and afp-test logs;
10. accept spurious empty logs;
11. prefer static Date_Format;
12. more formal directory content; clarified date format;
13. tuned error;
14. tuned;
15. misc tuning and clarification;