Copter: added DSM bind support

ArduCopter/GCS_Mavlink.cpp

@@ -1103,6 +1103,15 @@ void GCS_MAVLINK::handleMessage(mavlink_message_t* msg)
 
         switch(packet.command) {
 
+        case MAV_CMD_START_RX_PAIR:
+            // initiate bind procedure
+            if (!hal.rcin->rc_bind(packet.param1)) {
+                result = MAV_RESULT_FAILED;
+            } else {
+                result = MAV_RESULT_ACCEPTED;
+            }
+            break;
+
         case MAV_CMD_NAV_TAKEOFF: {
             // param3 : horizontal navigation by pilot acceptable
             // param4 : yaw angle   (not supported)