Changes

Summary

1. minor performance tuning, notably for Library.fold_string etc.;
2. clarified file name;
3. purge log files -- avoid old errors;
4. expose bibtex errors;
5. proper exception;
6. proper \isakeeptag (amending 13b5c3ff1954);
7. tuned;
8. NEWS;
9. merged
10. purge more carefully (amending 26f548370e8d); recovered 'display_drafts';
11. more error information according to @<Print type of token list@> in pdfweb.tex;
12. avoid redundant positions;
13. positions as postlude: avoid intrusion of odd %-forms into main tex source;
14. scan only one line, for more detailed positions;
15. purge more thoroughly;
16. option document_positions;
17. clarified file pattern;
18. ensure separation of TeX tokens;
19. simplified positions -- line is also human-readable in generated .tex file;
20. tuned message;
21. avoid excessive whitespace between antiquotations and text;
22. updated documentation;
23. more robust range on preceding comment-line; no range for blank lines; avoid recursive output_text/mark_range; clarified Latex.output_token (no range) vs. Thy_Output.present_token (with range);
24. proper file;
25. clarified file positions;
26. more operations;
27. tuned messages;
28. clean log file on Windows;
29. avoid println with its extra CR on Windows;
30. removed obsolete option (see 74a1b722507e);
31. re-implemented "isabelle document" in Isabelle/Scala, include latex_errors here;
32. removed Emacs legacy;
33. more robust Windows support;
34. more explicit latex errors;
35. some support for LaTeX;