Add more versatile URL handling

This adds highlighting to links.

I've also fixed the URL system so it can match more than one segment at a time.

I've also refactored a few things to simplify the code.

fixtures/frame/pages/[[...all]].js

@@ -3,6 +3,9 @@ import App from '../src/App';
 
 export default function Root() {
   const router = useRouter();
+  if (router.asPath === '/[[...all]]') {
+    return null;
+  }
   // We're gonna do our own routing.
-  return <App segments={router.query.all || []} />;
+  return <App url={router.asPath} />;
 }