Summary
- clarified init of settings vs. services;
- tuned message;
- merged
- another isabelle_scala_service;
- tuned;
- tuned -- avoid deprecated operations;
- more general support for isabelle_scala_service; clarified File_Format.registry;
- merged
- merged
- Added tag Isabelle2020-RC5 for changeset 8ed68b2aeba1
- more robust: notably for sledgehammer with 'using' and prover=cvc4;