Add warning when launching sick kerbals

[GarwelGarwel]

When going to launch a vehicle with kerbals that have low health and/or bad health conditions, display a warning (as a popup, on-screen message or with the message system).

[theonegalen]

I like this idea. At NASA, flight surgeons can ground crew members, but it should be up to us the players whether or not to use these sick crew. However , it seems like it would be logical to have a warning from the flight surgeons if you overrode them, like a good old-fashioned cya memo.