* Extract common ESLint settings into preset

* Mute excess eslint warnings

* Add ES5 compliance rules

We wish to forbid all uses of methods that were introduced after ES5
that IE11 doesn't support and requires polyfilling. The exceptions are
Map/Set/WeakMap/WeakSet as these classes are required to be polyfilled
for React already to support IE.

* Remove use of for-of and excessive Object.keys from schemaPredicates

* Remove use of Array.prototype.find from traversal.ts

* Add changeset