Added an implemention of basic state sorting to the RenderBin, but have commented

out the sort operation as Peformance benifit is currently negligable, will need
to improve on the sort functor to see real benifits.

include/osgUtil/RenderBin

@@ -47,7 +47,7 @@ class OSGUTIL_EXPORT RenderBin : public osg::Object
 
         void sort();
 
-        virtual void sort_local() {}
+        virtual void sort_local();
 
         virtual void draw(osg::State& state,RenderLeaf*& previous);