prefer system option: easier to make it default;

support multiple sessions, notably for "isabelle build -P -j2";

pretty formatting as in Isabelle/ML;

output prover messages;

clarified signature;

clarified signature: more robust;

proper parent base;

traditional print_mode for batch build;

proper support for "isabelle build -P Pure";

clarified signature: more robust bootstrap base;

proper startup for Pure: its use_prelude produces stdout before stderr protocol init;

proper context for loading Pure;

clarified signature of ML_Process vs. Isabelle_Process: proper support for "isabelle build -P -b";

close socket explicitly (idempotent);

more robust message_context and shutdown, e.g. after errors in protocol loop (see also 3f02bc5a5a03);

simplified code and proofs

automated proof

merged

cleaned proofs

clarified signature;

more accurate treatment of errors;

clarified modules: global quasi-scope for markers;

redunant simp rule

merged

more ugly old proofs

merged

tuned;

clarified modules;

clarified signature: more explicit type Protocol_Message.Marker;

tuned signature -- follow Scala;

tuned;

more explicit type Protocol_Message.Marker; tuned;

clarified protocol messages: explicitly use physical_writeln, always encode_lines;

tuned;

tuned whitespace;

more tidying up of old apply-proofs

merged

tuned;

tuned;

tuned;

eliminated pointless flag (see also 6533ceee4cd7);

tuned;

merged

structured a lot of ancient, horrible proofs

clarified Isabelle_Process phases;

clarified order: update syslog before handling exit;

tuned error message;

clarified signature: more robust startup_join;

merged

tuned;

misc tuning based on hints by IntelliJ IDEA;

clarified signature;

clarified signature;

clarified signature;

clarified signature;

tuned;