Changed "free population" in cities to "unassigned population" to be less confusing

android/assets/jsons/Translations/Other.json

@@ -862,7 +862,7 @@
 		Portuguese:"Bonus de crescimento"
 	}
 
-	"Free population":{ // as in "Free population: 2/13
+	"Unassigned population":{ // as in "Unassigned population: 2/13
 		Italian:"Popolazione libera"
 		Russian:"Свободное население"
 		French:"Population libre"

core/src/com/unciv/ui/cityscreen/CityScreen.kt

@@ -111,7 +111,7 @@ class CityScreen(internal val city: CityInfo) : CameraStageBaseScreen() {
         table.defaults().pad(5f)
         table.background=ImageGetter.getBackground(Color.BLACK.cpy().apply { a=0.8f })
         val columns = Stats().toHashMap().size
-        table.add(Label("{Free population}:".tr()
+        table.add(Label("{Unassigned population}:".tr()
                 +city.population.getFreePopulation().toString() + "/" + city.population.population,skin))
                 .colspan(columns).row()