Small issues to discuss/fix

[ammedd]

1. simulate_schedule.py l.251 time hardcoded
   time_costs.append(timedelta(minutes=20))
   Should come from ship_config.yaml l.16
   stationkeeping_time_minutes: 20.0

2. Would it be nice to set time delta and output for drifters and Argos? simulate_measurements l.87 and l.102
   outputdt=timedelta(hours=5), dt=timedelta(minutes=5),

3. Before there was the option to specify "max" as CTD_depth. Now should I advice students to set a depth more than their expected bathymetry? CTD.py l.27 and l.90
   Variable("max_depth", dtype=np.float32),
   Enhancement: Would be nice to set this separately for each CTD? And Argo drift_depth and drifter depth_meter as well in schedule.yaml. Then if not specified will be overwritten by ship_config?

4. XBT added to instruments but not to simulate_schedule and simulate_measurements?

5. Change ship speed to kts in config? Recompute to m/s in ship_config l.95