* Don't mix option chain with the prototype, simply expose it on the
instance. Actual code only exposed the `test` method to the user, and
that happens to be the default starting point anyway
* `run()` doesn't need to return stats
* Ensure `run()` always returns a promise, and does not throw
* Simplify `buildStats()`
* Derive chainable methods from the actual chain when generating the
TypeScript definition
* Don't bother prefixing methods / properties with underscores
Mark Wubben
48b892af02