- Fix copyright years.
- Sort imports
- "mailmanconf" -> "conf"
- Add "-o -" as a synonym for output to stdout
- Use Python 2.7 style {} format keys.
- Line folding.
- Do be sure to close the file in .process() since it could be called from API
  code.
- Clean up the docs.
- Add some tests.
- Acknowledge David Soto.