Massive JavaScript cleanup

- Use JSX for templates
- Docblock/comment everything
- Mostly passes ESLint (still some work to do)
- Lots of renaming, refactoring, etc.

CSS hasn't been updated yet.

js/lib/utils/mapRoutes.js

@@ -0,0 +1,21 @@
+/**
+ * The `mapRoutes` utility converts a map of named application routes into a
+ * format that can be understood by Mithril.
+ *
+ * @see https://lhorie.github.io/mithril/mithril.route.html#defining-routes
+ * @param {Object} routes
+ * @return {Object}
+ */
+export default function mapRoutes(routes) {
+  const map = {};
+
+  for (const key in routes) {
+    const route = routes[key];
+
+    if (route.component) route.component.props.routeName = key;
+
+    map[route.path] = route.component;
+  }
+
+  return map;
+}