Made the more of the OSG's referenced object desctructors protected to ensure

that they arn't created on the stack inappropriately.

Split the implemention of Matrix up so that it is a simple no referenced counted
class and can be safefly created on the stack.  To support referenced counting a
seperate subclass now exists, this is RefMatrix which inherits from both Matrix and
Object.

include/osg/CullingSet

@@ -35,8 +35,6 @@ class SG_EXPORT CullingSet : public Referenced
             }
         }
         
-        ~CullingSet();
-    
         typedef std::vector<ShadowVolumeOccluder>   OccluderList;
 
         typedef unsigned int Mask;
@@ -202,6 +200,8 @@ class SG_EXPORT CullingSet : public Referenced
         
     protected:
     
+        virtual ~CullingSet();
+
         Mask            _mask;
         Polytope        _frustum;
         OccluderList    _occluderList;