0.20.0
------
- Changes to allow multiple wheels with env.Clone(), for `nonstdlib` project
- Add target parameter to WhlFile

0.13.0
------
- Generate .tar.gz with zip-friendly post-1980 timestamps. Still need to set
  timestamps of zip for .whl instead of having zipfile read them from the
  filesystem.

0.10.0
------
- Remove dependency on wheel reference implementation (upstream is removing
  its API)

0.6.0
-----
- Tolerate missing optional metadata (written as 'UNKNOWN')
- Support src_root for sources in ./src/ etc.

0.5.0
-----
- Update enscons.setup2toml
- Support --dist-dir as needed by tox (write sdist to given directory)
- Improve documentation

0.4.0
-----
- Introduce env.Whl() to gather wheel members and env.WhlFile() to
  finish the archive
- Add env.SDist(source=...) to automatically name source archives.

