feat: testHook returns result ref object (testing-library#297)

feat: wrapper for testHook (testing-library#296)

* feat: wrapper for testHook

* Ignore eslint rule

fix(TS): typing of testHook (testing-library#292)

* Adds typing for testHook return

* Adds typings section to contributing.md

feat(testHook): modify testHook to return unmount function (testing-l…

…ibrary#290)

* Returns unmount function on testHook

* Adds test for unmount function; Adds example of useEffect

* Add Andrewmat as contributor

* Adds rerender on testHook return

fix: act polyfill for React 15.x (testing-library#288)

Fixes testing-library#287

fix(act): add a polyfill

Thanks @threepointone!

fix(build): upgrade all deps

Closes testing-library#279

fix: declare "module" field in package.json (testing-library#282)

**What**:

This change exposes the ESM version of the build, in the same fashion that the ES modules build is declared in `dom-testing-library`.

**Why**:

The ESM build is currently generated and distributed upon publish, though it is not exposed via `package.json`. My admittedly selfish use case for this is in having better heuristics around some linting rules (namely `import/named`).

**How**:
• Added the `module` field to `package.json`, pointing it at the path of the built artifact

**Checklist**:

- [ ] Documentation (N/A)
- [ ] Tests (N/A)
- [x] Ready to be merged
- [x] Added myself to contributors table

**&c.**:

Thanks for this library–it's great! Let me know if there's anything I overlooked or you would like to see changed.

test: fix test coverage and testHook tests

Sorry @donavon, this is the best we can do I think :-(

fix(TS): add explicit annotation to Query type (testing-library#260)

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