love for all things Zeus, multi civ classes

• new: allow multiple civ classes to be set (they will randomly be chosen from)
• new: ZEN context actions for
  • Dismiss civilian (i.e. remove GRAD Civs magic without despawning them)
  • Stop (stops civs dead in their tracks)
  • Continue (makes Civs get on with whatever their task is after stopping them)
• fix: properly declare ZEN dependency
• fix: error message on transit despawn
• cleanup: icons for Zeus modules, re-categorize them, move all ZEN deps into a "zeus" addon