MISSION_PLANNING: if to elif in executeTimedLoop method

Doesn't change anything functionally (the two original "if" statements
are mutually exclusive), but it just cleans up the code some.

ap_mission_planning/src/ap_mission_planning/swarm_manager.py

@@ -363,7 +363,7 @@ class SwarmManager(nodeable.Nodeable):
                             cmd = behavior.compute_command()
                             if isinstance(cmd, brgmsg.LLA):
                                 self.__publish_wpt(cmd)
-                            if isinstance(cmd, brgmsg.LLAS):
+                            elif isinstance(cmd, brgmsg.LLAS):
                                 self.__publish_spd_wpt(cmd)
                             elif isinstance(cmd, stdmsg.UInt16):
                                 self.__publish_wpt_id(cmd)