Fixed NotImplementedException when attempting to clone linked submarines

Barotrauma/BarotraumaShared/Source/Map/LinkedSubmarine.cs

@@ -99,7 +99,12 @@ namespace Barotrauma
         {
             return Vector2.Distance(position, WorldPosition) < 50.0f;
         }
-        
+
+        public override MapEntity Clone()
+        {
+            return CreateDummy(Submarine, filePath, Position);
+        }
+
         private void GenerateWallVertices(XElement rootElement)
         {
             List<Vector2> points = new List<Vector2>();

Barotrauma/BarotraumaShared/Source/Map/MapEntity.cs

@@ -163,10 +163,7 @@ namespace Barotrauma
             return (Submarine.RectContains(WorldRect, position));
         }
 
-        public virtual MapEntity Clone()
-        {
-            throw new NotImplementedException();
-        }
+        public abstract MapEntity Clone();
 
         public static List<MapEntity> Clone(List<MapEntity> entitiesToClone)
         {