Reorganize mdv and observe packages

pkg/mdv/lib/src/node.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of mdv;
+
+/** Extensions to the [Node] API. */
+class _NodeExtension {
+  final Node node;
+
+  _NodeExtension(this.node);
+
+  /**
+   * Binds the attribute [name] to the [path] of the [model].
+   * Path is a String of accessors such as `foo.bar.baz`.
+   */
+  void bind(String name, model, String path) {
+    window.console.error('Unhandled binding to Node: '
+        '$this $name $model $path');
+  }
+
+  /** Unbinds the attribute [name]. */
+  void unbind(String name) {}
+
+  /** Unbinds all bound attributes. */
+  void unbindAll() {}
+
+  TemplateInstance _templateInstance;
+
+  /** Gets the template instance that instantiated this node, if any. */
+  TemplateInstance get templateInstance =>
+      _templateInstance != null ? _templateInstance :
+      (node.parent != null ? node.parent.templateInstance : null);
+}