Useless function find, maybe delete?

Signed-off-by: Bergé <corentin.berge@outlook.fr>

include/dynamic-graph/signal-ptr.h

@@ -62,9 +62,10 @@ namespace dynamicgraph
     const SignalBase<Time>* getAbstractPtr () const; // throw
     virtual void plug( SignalBase<Time>* ref );
     virtual void unplug () { plug(NULL); }
-    virtual bool isPluged () const DYNAMIC_GRAPH_DEPRECATED {
+    //Useless function, didn't find any use of this one
+    /*virtual bool isPluged () const DYNAMIC_GRAPH_DEPRECATED {
       return isPlugged ();
-    }
+    }*/
     virtual bool isPlugged () const { return (NULL!=signalPtr); }
     virtual SignalBase<Time>* getPluged () const { return signalPtr; }
     virtual bool isAbstractPluged () const;