- alien ruin structure drawing order changes

- placing cargo items using syncedRand (items will be in the same position for all clients)
- less confusing waypoint/spawnpoint editing (spawnpoints can't be converted to waypoints or vice versa, and spawnpoint settings aren't shown for waypoints)
- more informative message about missing cargo spawnpoints

Subsurface/Source/Events/Missions/CargoMission.cs

@@ -70,7 +70,7 @@ namespace Barotrauma
             }
 
             Vector2 position = new Vector2(
-                Rand.Range(cargoRoom.Rect.X + 20, cargoRoom.Rect.Right - 20, true),
+                Rand.Range(cargoRoom.Rect.X + 20, cargoRoom.Rect.Right - 20, false),
                 cargoRoom.Rect.Y - cargoRoom.Rect.Height + 10.0f);
 
             var item = new Item(itemPrefab, position, cargoRoom.Submarine);