Add TRACEROUTE_APP portnum

portnums.proto

@@ -133,6 +133,12 @@ enum PortNum {
    */
   SIMULATOR_APP = 69;
 
+  /*
+   * Provides a traceroute functionality to show the route a packet towards
+   * a certain destination would take on the mesh.
+   */
+  TRACEROUTE_APP = 70;
+
   /*
    * Private applications should use portnums >= 256.
    * To simplify initial development and testing you can use "PRIVATE_APP"