ConfirmLandingState

	- allow a bit of randomness in terrain choice from Globe texture.
BattlescapeGenerator: accept input of worldTerrain from above.
	- left nextStage() untouched for now ....
	- init _rules w/ Ruleset
Ufo: save that terrain to savedgame file.
AlienMission: set empty string for terrain if UFO lifts.

BattleItem: default XCOMProperty var to true.

Terrain_Pack: "terrains" accepts multiple terrains and will choose from them.
en-US: tweak UFO-name strings.