Ensure machine has writable items

SabreTools.Library/DatFiles/DatFile.cs

@@ -3793,6 +3793,27 @@ namespace SabreTools.Library.DatFiles
             return Enum.GetValues(typeof(ItemType)) as ItemType[];
         }
 
+        /// <summary>
+        /// Get if a machine contains any writable items
+        /// </summary>
+        /// <param name="datItems">DatItems to check</param>
+        /// <returns>True if the machine contains at least one writable item, false otherwise</returns>
+        /// <remarks>Empty machines are kept with this</remarks>
+        protected bool ContainsWritable(List<DatItem> datItems)
+        {
+            // Empty machines are considered writable
+            if (datItems == null || datItems.Count == 0)
+                return true;
+
+            foreach (DatItem datItem in datItems)
+            {
+                if (GetSupportedTypes().Contains(datItem.ItemType))
+                    return true;
+            }
+
+            return false;
+        }
+
         /// <summary>
         /// Get if an item should be ignored on write
         /// </summary>