* Mesh: new sendFlood() overload with transport codes.

* BaseChatMesh:  sendFloodScoped(), for overriding with some outbound 'scope' / TransportKey
* companion: new 'send_scope' variable.

src/Mesh.h

@@ -186,6 +186,12 @@ public:
   */
   void sendFlood(Packet* packet, uint32_t delay_millis=0);
 
+  /**
+   * \brief  send a locally-generated Packet with flood routing
+   * \param transport_codes   array of 2 codes to attach to packet
+  */
+  void sendFlood(Packet* packet, uint16_t* transport_codes, uint32_t delay_millis=0);
+
   /**
    * \brief  send a locally-generated Packet with Direct routing
   */