add NsUnknown::Dispose

src/core/ns-unknown.cc

@@ -136,6 +136,12 @@ NsUnknown::Unref (void)
   m_impl->Unref ();
 }
 
+void 
+NsUnknown::Dispose (void)
+{
+  // we do not do anything by default.
+}
+
 void
 NsUnknown::RefInternal (void)
 {

src/core/ns-unknown.h

@@ -58,6 +58,8 @@ public:
    * will be found by the same reference count.
    */
   void AddInterface (NsUnknown *interface);
+
+  virtual void Dispose (void);
 protected:
   /**
    * \param iid the Interface Id of the interface defined by a direct subclass