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/DOFTransform

@@ -107,6 +107,7 @@ class SG_EXPORT DOFTransform : public Transform
         virtual bool computeWorldToLocalMatrix(Matrix& matrix,NodeVisitor* nv) const;
 
     protected:
+
         virtual ~DOFTransform() {}
 
         Vec3 _minHPR;