Clean up OOCharacter

Mostly style changes, and hiding of internal methods. Also removed
longDescription property; it was never used and the setup code was
broken.
Reform ship crew setup

Adds a convenience method for the common case, which two changes:
* It does nothing for unpiloted ships
* It uses the ship's nominal home system rather than the current
  system as the character's origin seed. I don't think this can
  make a difference currently, but it's future-proofing.
Unpilotedness reform

* Rename isUnpiloted to isExplicitlyUnpiloted
* Add more general isUnpiloted method covering things like rocks.