Merge pull request #1434 from paparazzi/mavlink_protocol_cleanup

update the Paparazzi specific mavlink messages
- remove `len` field from `SCRIPT_ITEM`
- report current block with `SCRIPT_CURRENT` message

sw/airborne/modules/datalink/missionlib/blocks.c

@@ -50,9 +50,10 @@ void mavlink_send_block(uint16_t seq)
     static const char *blocks[] = FP_BLOCKS;
     char block_name[50];
     strncpy(block_name, blocks[seq], 49); // String containing the name of the block
-    uint8_t len = strlen(blocks[seq]); // Length of the block name
+    // make sure the string is null terminated if longer than 49chars
+    block_name[49] = 0;
     mavlink_msg_script_item_send(MAVLINK_COMM_0, mission_mgr.rem_sysid, mission_mgr.rem_compid,
-                                 seq, len, block_name);
+                                 seq, block_name);
     MAVLinkSendMessage();
     MAVLINK_DEBUG("Sent BLOCK_ITEM message: seq %i, name %s\n", seq, block_name);
   } else {

sw/airborne/modules/datalink/missionlib/mission_manager.c

@@ -92,7 +92,8 @@ void mavlink_mission_periodic(void)
   // FIXME: really use the SCRIPT_ITEM message to indicate current block?
   if (mission_mgr.current_block != nav_block) {
     mission_mgr.current_block = nav_block;
-    mavlink_send_block(nav_block); // send the current block seq
+    mavlink_msg_script_current_send(MAVLINK_COMM_0, nav_block);
+    MAVLinkSendMessage();
   }
   // check if we had a timeout on a transaction
   if (sys_time_check_and_ack_timer(mission_mgr.timer_id)) {