Change in CcnxApp API.  Now callbacks also contain pointer of original
packet (useful to get packet tags, if they exist)

Reflecting changes in PackegTag API

Rescanning bindings

More work on packet-path-weight tracers
diff --git a/model/annotated-topology-reader.h b/model/annotated-topology-reader.h
index eccbc29..6edcb34 100644
--- a/model/annotated-topology-reader.h
+++ b/model/annotated-topology-reader.h
@@ -65,7 +65,7 @@
   /**
    * \brief Get links read by the reader
    */  
-  std::list<Link>
+  const std::list<Link>&
   GetLinks () const;
   
   /**