Improved the speed of the ValueObject get/setting by utilizing typeid() and static_cast<> in place of original dynamic_cast<>'s

include/osg/UserDataContainer

@@ -39,6 +39,14 @@ class OSG_EXPORT UserDataContainer : public osg::Object
             by derived classes.*/
         virtual const char* className() const  { return "UserDataContainer"; }
 
+        /** Convert 'this' into a UserDataContainer pointer if Object is a UserDataContainer, otherwise return 0.
+          * Equivalent to dynamic_cast<UserDataContainer*>(this).*/
+        virtual UserDataContainer* asUserDataContainer() { return this; }
+
+        /** convert 'const this' into a const UserDataContainer pointer if Object is a UserDataContainer, otherwise return 0.
+          * Equivalent to dynamic_cast<const UserDataContainer*>(this).*/
+        virtual const UserDataContainer* asUserDataContainer() const { return this; }
+
         /**
          * Set user data, data must be subclassed from Referenced to allow
          * automatic memory handling.  If your own data isn't directly
@@ -209,7 +217,6 @@ inline const Object* getUserObject(const osg::Object* object, const std::string&
     return udc ? udc->getUserObject(name) : 0;
 }
 
-
 }
 
 #endif