* Add Prettier, with basic config and ESLint integration
* Apply Prettier to all files using `yarn lint --fix`
* Tell Prettier to ignore an empty text in a test output.
* Run Prettier on JS files not handled by ESLint, and lint them too
* rename state to value in slate core, as deprecation
* rename all references to state to value in slate core
* migrate slate-base64-serializer
* migrate slate-html-serializer
* migrate slate-hyperscript
* migrate slate-plain-serializer
* migrate slate-prop-types
* migrate slate-simulator
* fix change.setState compat
* deprecate references to state in slate-react
* remove all references to state in slate-react
* remove `value` and `schema` from props to all components
* fix default renderPlaceholder
* fix tests
* update examples
* update walkthroughs
* update guides
* update reference
* remove data from event handler signatures
* standardize known transfer types
* add setEventTransfer to docs
* update examples, fix drag/drop
* fix tests and draggable attribute setting
* Allow React 16 in peerDeps and use it for dev
* Make tests pass with React 16
Changes are cosmetic:
- React 16 no longer adds a trailing `;` to `style` attributes
- React 16 outputs `0` and not `0px` for sizes in `style`
* Reshape void component structure.
Get rid of offscreen spacer.
* Polish Embeds example `Video` component.
* Fix oversight.
* Force spacer width to be 0.
* Update tests