The `with-flow` sample has some obsolete definitions which are unused by the sample code. Removing the un-imported declarations is the easiest approach.
Changes:
* updated packages
* moved the content of `layout` to `_app.js` and created simple `Page` component
* replaced `import * as React` because it is not necessary to import everything
* moved `next.js.flow` to `flow-typed` as it is default directory for library definitions
* updated the gif