Added Transport close method
diff --git a/ndn-cpp/transport/Transport.hpp b/ndn-cpp/transport/Transport.hpp
index af1a2c0..dedfffd 100644
--- a/ndn-cpp/transport/Transport.hpp
+++ b/ndn-cpp/transport/Transport.hpp
@@ -25,6 +25,11 @@
   {
     send(&data[0], data.size());
   }
+  
+  /**
+   * Close the connection.  This base class implementation does nothing, but your derived class can override.
+   */
+  virtual void close();
 };
 
 }