Cleaned up heartbeatOnlyCount placement

 - previous implementation relied on there actually being some message
not handled by the switch in order to fall into the default case and
reset the heartbeatOnly counter
Replaced magic numbers with existing enums
Reinstated @property hearbeatOnlyCount
Corrected invalid waypoint

 - 0/HOME does not appear to be a valid waypoint type
 - switched to 22/TAKEOFF
Respect MAVLink retransmission protocol during mission transmission requests

 - also specify a different component id for the ground station