Changes

Summary

1. tuned;
2. tuned signature;
3. proper return code for timeout (amending f868f12f9419);
4. retain tail out_lines as printed, but not the whole log content;
5. explicit class Build_Results; cancelled sessions have rc = 1 (again);
6. more informative Build.build_results; tuned signature;
7. more informative Process_Result; tuned;
8. clarified modules;
9. tuned signature;