Changes

Summary

1. merged
2. build on macbroy2 for performance, but use macbroy30 for its more robust hdiutil;
3. makedist_bundle works on Linux as well: build dmg on remote Mac;
4. added isabelle remote_dmg tool;
5. proper type for Library.using; tuned signature;
6. support user@host syntax;
7. modernized date format;
8. tuned signature;
9. eliminated extra trim_line: Process_Result.out/err are based on cat_lines, without trailing newline;
10. support for remote tmp dirs;
11. close more thoroughly;
12. provide execute operation, similar to Isabelle_System.bash;
13. proper support for exec channel (see also bash.scala);
14. proper hierarchic names;
15. more Sftp operations;
16. more specific channels; more Sftp operations;
17. clarified treatment of options; more uniform channels;
18. support for remote command execution; tuned;
19. tuned;
20. more generous timeout default (see also jEdit/FTP);
21. connect session by default; tuned signature;
22. clarified (hardwired!) default (see also jEdit/FTP);
23. tuned comment;
24. support for SSH in Isabelle/Scala;