Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/underscore/modules/mapObject.js

@@ -0,0 +1,16 @@
+import cb from './_cb.js';
+import keys from './keys.js';
+
+// Returns the results of applying the `iteratee` to each element of `obj`.
+// In contrast to `_.map` it returns an object.
+export default function mapObject(obj, iteratee, context) {
+  iteratee = cb(iteratee, context);
+  var _keys = keys(obj),
+      length = _keys.length,
+      results = {};
+  for (var index = 0; index < length; index++) {
+    var currentKey = _keys[index];
+    results[currentKey] = iteratee(obj[currentKey], currentKey, obj);
+  }
+  return results;
+}