v4.0.0

If you are upgrading: please see UPGRADING.md.

Changed

• Breaking: bump readable-stream from 3 to 4 (082b8d6) (Vincent Weevers)
• Breaking: use classes, requiring new (dafafb2) (Vincent Weevers)
• Breaking: drop Node.js 10 (817c30c) (Vincent Weevers)

Fixed

• Cleanup README and add missing docs for options (94a2a8e) (Vincent Weevers).