New Features:
- license changed from BSD-3 Clause to Apache-2.0
- implements draft 2020-12 specification
- implement output formats flag, basic and detailed
- cmd/jv: add -output flag
- extract $comment, writeOnly, deprecated metadata annotations
Incompatible Changes:
- if no $schema specified, default to Draft2020
- replaced SchemeNotRegisteredError with LoaderNotFoundError
- ValidateInterface method renamed to Validate
- ValidationError now captures keywordLocations