Changed the version strings to use OpenSceneGaph rather than "Open Scene Graph"

src/osgProducer/Version.cpp

@@ -8,5 +8,5 @@ const char* osgProducerGetVersion()
 
 const char* osgProducerGetLibraryName()
 {
-    return "Open Scene Graph Producer Library";
+    return "OpenSceneGraph Producer Library";
 }

src/osgProducer/Viewer.cpp

@@ -589,7 +589,7 @@ void Viewer::update()
 
         // update the scene by traversing it with the the update visitor which will
         // call all node update callbacks and animations.
-        getSceneData()->accept(*_updateVisitor);
+        getTopMostSceneData()->accept(*_updateVisitor);
     }
     
     // update the main producer camera