v2.0.0

• Change drag.on to pass the event directly to listeners.
• Upgrade to d3-selection 2.

See https://observablehq.com/@d3/circle-dragging-ii for an example.

This release adopts ES2015 language features such as for-of and drops support for older browsers, including IE. If you need to support pre-ES2015 environments, you should stick with d3-brush 1.x or use a transpiler.