### Added

- Make use of a source's (optional) provenance field
- Add license extraction support
- Add --spdx-comment option
- Add element name as externalRef

### Changed

- Don't use the BST environment variable
- Check creators are in the spdx format
- Drop special casing of patch sources
- Set fallback package name to 'UNKNOWN' for sources
  - docker images are currently the only known "unknown"