Move Character Portrait nulls to end of list

Assets/Fungus/Scripts/Components/Character.cs

@@ -183,8 +183,11 @@ namespace Fungus
         #endregion
 
         protected virtual void OnValidate()
+        {
+            if (portraits != null && portraits.Count > 1)
             {
                 portraits.Sort(PortraitUtil.PortraitCompareTo);
             }
         }
     }
+}

Assets/Fungus/Scripts/Utils/PortraitUtils.cs

@@ -189,9 +189,9 @@ namespace Fungus
             if (x == y)
                 return 0;
             if (y == null)
-                return 1;
-            if (x == null)
                 return -1;
+            if (x == null)
+                return 1;
 
             return x.name.CompareTo(y.name);
         }