Add support for Creuss hero

[SephHawkins]

When there is a map, using the Creuss hero should allow specifying which systems need to be swapped.

• [x] Allow swapping any two systems in the map
• [x] Allow swapping with the Wormhole Nexus, if it's been replaced by the Muaat hero.
• [x] Allow swapping a home system with the Wormhole Nexus, if it's been replaced by the Muaat hero.
• [x] Prevent swapping Hyperspace tiles if present.