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/amd/property.js

@@ -0,0 +1,14 @@
+define(['./_deepGet', './_toPath'], function (_deepGet, _toPath) {
+
+  // Creates a function that, when passed an object, will traverse that object’s
+  // properties down the given `path`, specified as an array of keys or indices.
+  function property(path) {
+    path = _toPath(path);
+    return function(obj) {
+      return _deepGet(obj, path);
+    };
+  }
+
+  return property;
+
+});