WIP proposal: Router

[gordonbrander]

This PR explores adding a minimal history-API-based router, intended to be used in tandem with store.

TODO

• [ ] Push state router
• [ ] Integration with store
• [ ] Dynamic path matching
• [ ] Link interception via attribute (data-route?)

Prior art

• https://developer.chrome.com/docs/web-platform/urlpattern
• https://css-tricks.com/native-javascript-routing/
• https://github.com/krasimir/navigo
• https://router.vuejs.org/

DSL bikeshedding

Express style?

const router = Router()

router.route(`api/object/:id`, request => {
  // Do something... send message to store, replace root element, etc.
})

const unlisten = router.listen()