add download progress, improbable cloud browser, lock touch when pencil is down on iOS

engine/node.h

@@ -194,6 +194,7 @@ public:
     virtual void init();
     virtual void loaded();
     virtual void added(Node* parent);
+    virtual void removed(Node* parent);
     const Node* init_template(const char* id);
     void async_start();
     void async_update();