Publishing release 21-0.9.
- Significant updates to the OpenJML User Guide, with corrections and updates to the API behavior of OpenJML to match
- Reorganizations of source and test code
- Fixed the check of loop_invariants after loop exit
- Removed --silent, --logic, --new-as-pure
- Fixed -no-jml
- Added --properties, \choosex
- Added missing tests for various options