Feature Request: Switching 37\38 expeditions

[Nuts123]

It would be nice to add an option to switch between the 37 and 38 expeditions

[mrmin123]

Note to self/musings:

• Use of something like the existing done_expeditions (except on a per-fleet basis) and modulo operator would theoretically make it easy to cycle through a list of expeditions assigned to a fleet
  • Needs done_expeditions on a per-fleet basis; probably store in Expedition object
• Problem is ensei_factory; currently Enseis are defined and assigned to a fleet on Expedition instantiation... maybe create a list of Enseis per fleet on Expedition instantiation, and choose the specific Ensei from the main loop