clarified signature: allow more general init, e.g. from existing database;

clarified signature: allow to provide session_heaps by different means, e.g. from tmp directory or alternative session structure;

tuned;

simplified somewhat pointless error message (see also 0189fe0f6452);

clafified signature: simplify object-oriented reuse;

revert pointless 375c6b9ce9ea: overall thread context is already uninterruptible (see 54ac957c53ec);

tuned whitespace;

merged

Fixed a presentation error

Importation of basic group theory results, due to Jakob von Raumer from his AFP entry Jordan-Hölder Theorem

tuned whitespace;

tuned;

clarified signature, although "sql" argument is de-facto mandatory;

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;

support for build database: still inactive; more detailed Build_Job.Node_Info;

tuned signature;

clarified signature: more robust operations;

tuned;

tuned;

more operations;

clarified signature: more operations;

clarified signature;

clarified signature: more robust (see also cf2ef4be3630);

unused (see also 7b318273a4aa and a1fb4d28e609);

tidying ugly proofs

brought back [...] maplet syntax

merged

has_sum now an infix operator!!

merged

New material contributed by Manuel

Map.empty no longer output abbreviation; %_. None is shorter and requires no explanation