Add GetRenderer to core

src/core/core.h

@@ -55,6 +55,8 @@ namespace VideoDumper {
 class Backend;
 }
 
+class RendererBase;
+
 namespace Core {
 
 class Timing;
@@ -170,6 +172,8 @@ public:
         return *dsp_core;
     }
 
+    RendererBase& Renderer();
+
     /**
      * Gets a reference to the service manager.
      * @returns A reference to the service manager.