Added a AnimationPathCallback which can update both a MatrixTransform and a

PositionAttitudeTransform, removed the equivialnt callbacks once found in these
transform classes.

Changed the NodeCallback class so its derived from osg::Object instead of
osg::Referenced to allow it to be saved out in the .osg format.

Added support for Update and Cull callbacks into the .osg file format.

Added support for AnimationPathCallback into the .osg file format.

include/osg/NodeCallback

@@ -5,7 +5,7 @@
 #ifndef OSG_NODECALLBACK
 #define OSG_NODECALLBACK 1
 
-#include <osg/Referenced>
+#include <osg/Object>
 #include <osg/ref_ptr>
 
 namespace osg {
@@ -13,13 +13,18 @@ namespace osg {
 class Node;
 class NodeVisitor;
 
-class SG_EXPORT NodeCallback : public virtual Referenced {
+class SG_EXPORT NodeCallback : public virtual Object {
 
     public :
     
 
         NodeCallback(){}
-        virtual ~NodeCallback() {}
+
+        NodeCallback(const NodeCallback&,const CopyOp&):
+            _nestedCallback(_nestedCallback) {}
+
+        
+        META_Object(osg,NodeCallback)
         
         
         /** Callback method call by the NodeVisitor when visiting a node.*/
@@ -71,6 +76,10 @@ class SG_EXPORT NodeCallback : public virtual Referenced {
    public:
 
         ref_ptr<NodeCallback> _nestedCallback;
+        
+    protected:
+    
+        virtual ~NodeCallback() {}
 };
 
 } // namespace