Move parsing to new class

SabreTools.DatFiles/DatFile.Updating.cs

@@ -454,6 +454,7 @@ namespace SabreTools.DatFiles
         /// <returns>List of DatHeader objects representing headers</returns>
         public List<DatHeader> PopulateUserData(List<ParentablePath> inputs)
         {
+            DatTool dt = new DatTool();
             DatFile[] datFiles = new DatFile[inputs.Count];
             InternalStopwatch watch = new InternalStopwatch("Processing individual DATs");
 
@@ -463,7 +464,7 @@ namespace SabreTools.DatFiles
                 var input = inputs[i];
                 logger.User($"Adding DAT: {input.CurrentPath}");
                 datFiles[i] = Create(Header.CloneFiltering());
-                datFiles[i].Parse(input, i, keep: true);
+                dt.ParseInto(datFiles[i], input, i, keep: true);
             });
 
             watch.Stop();