tuned;

proper SQL (amending 7ab9bac1ca96);

clarified signature: more explicit "synchronized" regions;

more robust interrupt handling, notably for Build_Job.terminate();

clarified signature: works for general Build_Job;

tuned;

clarified modules;

clarified signature;

proper log_lines, without protocol messages (amending cb3f5361fbca);

clarified signature;

tuned messages;

clarified error output vs. process_result stored in build_database (see also 13a0f537e232 and bff56eae3ec5);

clarified system option: guard for testing, until the database layout has stabilized;

merged

Simplified some proofs

clarified db content: avoid redundancy of historic ML_IDENTIFIER;

merged

proper filterNot, not filterNot-not;

option build_hostname allows to change hostname easily;

clarified permissions of build.db, following server.db;

enforce rebuild of Isabelle/ML, after various changes to build database management;

misc tuning and clarification: more uniform use of optional "sql" in SQL.Table.delete/select;

tuned: fewer warnings in IntelliJ IDEA;

clarified init_database vs. update_database: implicitly assume fresh "instance";

clarified Build_Process.Context: cover all static information;

tuned whitespace in generated SQL;

tuned: prefer typed operations;

clarified signature: more concise operations;

more robust options in "prefs" format: avoid odd control character;

proper settings for hostname: allow to adjust it in user space;