Added

• Run test suite in TypeScript in addition to Node.js (@vweevers)
• Add TypeScript smoke test (@vweevers)
• Add TypeScript readme section with stability badge (@vweevers)

Fixed

• Update TypeScript typings for v4 (@vweevers)
• Use ES6 classes in tests to please TypeScript (@vweevers)
• Define default methods on prototype to please TypeScript (@vweevers)

Removed

• Remove obsolete parameters from tests (@vweevers)

Historical Note This was released as a patch because it only changed tests
and TypeScript typings (which are marked experimental and don't follow semver).