Summary
- UHD is standard, HD non-standard;
- updated for release;
- merged
- Added tag Isabelle2019-RC0 for changeset 6f2ab7f150f6
- updated for release;
- eliminated hard TABs;
- updated for release;
- tuned;
- The order of a group now follows the HOL Light definition, which is more general
- merged
- merged
- some new group theory results: integer group, trivial group, etc.
- more convenient export;
- misc tuning for release;
- more material for release;
- misc tuning for release;