Compatibility for 2.3
Removed changes to orbital habitats, since paradox overhauled them with this latest patch.

Attempted to force AI to build only one of each kind of habitat. Testing is extremely slow, so this has only been minimally tested.

Fixed leisure districts so that Warrior Culture provides duelists there as well.

Just fixing errors...

This time I REALLY fixed the rare crystal mining tech not appearing when you had a rare-crystal asteroid habitat in your empire...

Also, I added in a couple of missing gridbox icons for habitat housing.

Fixed the rare crystal mining technology again... more thoroughly this time.

Fixed the rare crystal technology not appearing when a country owns a rare crystal asteroid habitat.

Updated Holo-theatres to include Duelists.

Updated the error text for colonization limit on planetary habitats decisions.

Made grid boxes different colors.

All habitat types now share a single 10-pop requirement colonization limit.
Updated building overrides to 2.2.6 versions.
Added conversion code, so districts change on ownership change.