Wire render worker pool into render manager

app/render/rendermanager.h

@@ -69,6 +69,8 @@ private:
 	ShaderCache *shader_cache_;
 };
 
+class RenderWorkerPool;
+
 class RenderManager : public QObject {
 	Q_OBJECT
 public:
@@ -76,6 +78,9 @@ public:
 		/// Graphics acceleration provided by OpenGL
 		kOpenGL,
 
+		/// Video frames are rendered by an external olive-render-worker process.
+		kMultiProcess,
+
 		/// No graphics rendering - used to test core threading logic
 		kDummy
 	};
@@ -246,6 +251,8 @@ private:
 
 	PreviewAutoCacher *auto_cacher_;
 
+	RenderWorkerPool *worker_pool_;
+
 private slots:
 	void ClearOldDecoders();
 };