Return new string to avoid losing the reference

NETCLASSes are stored as shared pointers.  We lose the reference as soon
as the pointer count decrements to 0, which can happen immediately when
the shared pointer is returned.

include/netclass.h

@@ -62,7 +62,7 @@ public:
         return wxT( "NETCLASS" );
     }
 
-    const wxString& GetName() const { return m_Name; }
+    const wxString GetName() const { return m_Name; }
     void SetName( const wxString& aName ) { m_Name = aName; }
 
     /**