Bodyswap Improvements and Additions

[Crystalwarrior]

• If bodyswap is ran with no arguments, bring up a list of units on the map to bodyswap to
• Bodyswapping adjusts the extra members list, not core party - consistent with vanilla behavior for retiring/unretiring with core party.
• Reveal tiles near the bodyswapped unit
• When bodyswapping to someone with no name, forcibly give them a name