Draft groups in layers menu

TODO: don't use Bootstrap's switches!!

js/utils/nodeUtils.js

@@ -66,11 +66,11 @@ function traverseTree(node, flatList, depth = 1, inheritedColor = null) {
  * Create a flat list of nodes from
  * the nested structure in config
  * @param {Array} nodes
- * @returns {{flat: NormalizedSceneNode[], normNode: object}} A flat list of nodes
+ * @returns {{flat: NormalizedSceneNode[], tree: NormalizedSceneNode[]}} A flat list of nodes
 **/
 export function normalizeNodes (nodes) {
     let flatList = [];
     const normNode = traverseTree(nodes, flatList);
 
-    return {flat: flatList, normNode};
+    return {flat: flatList, tree: normNode.children};
 }