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/NodeCallback

@@ -73,7 +73,7 @@ class SG_EXPORT NodeCallback : public virtual Object {
             }
         }
         
-   public:
+    public:
 
         ref_ptr<NodeCallback> _nestedCallback;