AG-1053 Tidy react examples, make more idiomatic

src-examples/NavItem.jsx

@@ -0,0 +1,20 @@
+import React from 'react'
+import * as PropTypes from 'prop-types';
+import {Route, Link} from 'react-router-dom'
+
+// for bootstrap li active functionality
+export default function NavItem({children, to, exact}) {
+    return (
+        <Route path={to} exact={exact} children={({match}) => (
+            <li className={match ? 'active' : null}>
+                <Link to={to}>{children}</Link>
+            </li>
+        )}/>
+    )
+}
+
+NavItem.propTypes = {
+    to: PropTypes.string.isRequired,
+    exact: PropTypes.bool,
+    children: PropTypes.node.isRequired,
+};