Defeat improvements (#1654)

* Fix: civilization not being destroyed when disbanding the initial settler

* Fix: destroyed unit providing visibility until the end of the turn

core/src/com/unciv/logic/map/MapUnit.kt

@@ -416,6 +416,7 @@ class MapUnit {
     fun destroy(){
         removeFromTile()
         civInfo.removeUnit(this)
+        civInfo.updateViewableTiles()
     }
 
     fun removeFromTile(){
@@ -470,6 +471,7 @@ class MapUnit {
         destroy()
         if(currentTile.getOwner()==civInfo)
             civInfo.gold += baseUnit.getDisbandGold()
+        if (civInfo.isDefeated()) civInfo.destroy()
     }
 
     private fun getAncientRuinBonus(tile: TileInfo) {