make sure the volfog manager is dead before we kill scene

Engine/source/scene/sceneManager.cpp

@@ -50,6 +50,7 @@ MODULE_BEGIN( Scene )
 
    MODULE_INIT_AFTER( Sim )   
    MODULE_SHUTDOWN_AFTER( Sim )
+   MODULE_SHUTDOWN_AFTER( VolumetricFogRTManager )
    
    MODULE_INIT
    {