sweeping node graph changes for new rendering pipeline

The new rendering pipeline strives to simplify the nodes themselves as much
as possible and move much of the logic to an external rendering engine. This
change removes all of the responsibilities that no longer belong to the
nodes themselves and will soon be folded into the renderer.

app/render/backend/opengl/openglworker.cpp

@@ -66,9 +66,9 @@ void OpenGLWorker::Render(const NodeDependency &path)
 
   // Lock all Nodes to prevent UI changes during this render
   foreach (Node* dep, all_deps) {
-    dep->Lock();
+    dep->LockUserInput();
   }
-  node->Lock();
+  node->LockUserInput();
 
   // FIXME: Write traversal code
 
@@ -77,9 +77,9 @@ void OpenGLWorker::Render(const NodeDependency &path)
 
   // Unlock all Nodes so changes can be made again
   foreach (Node* dep, all_deps) {
-    dep->Unlock();
+    dep->UnlockUserInput();
   }
-  node->Unlock();
+  node->UnlockUserInput();
 
   // Now we need the texture done so we call glFinish()
   functions_->glFinish();
@@ -111,3 +111,7 @@ void OpenGLWorker::FinishInit()
 
   qDebug() << "Context in" << ctx_->thread() << "successfully finished";
 }
+
+void OpenGLWorker::RenderAsSibling(const NodeDependency &)
+{
+}