Added BaseType "Attribute" to DNAClassAttribute generator function and regenerated the source.

BlendFile/DNAClassAttribute.cs

@@ -13,7 +13,7 @@ using System;
 namespace BlendFile {
     
     [AttributeUsage(AttributeTargets.Class)]
-    public class DNAClassAttribute {
+    public class DNAClassAttribute : System.Attribute {
         private int _originalIndex;
         public virtual int OriginalIndex {
             get {

CodeGenerator/Program.cs

@@ -245,9 +245,11 @@ namespace CodeGenerator {
                 IsClass = true,
                 Attributes = MemberAttributes.Public
             };
+            ctd.BaseTypes.Add(new CodeTypeReference(typeof(Attribute)));
             ctd.CustomAttributes.Add(new("AttributeUsage",
                 new CodeAttributeArgument(new CodeSnippetExpression("AttributeTargets.Class"))));
             
+
             var cmf = new CodeMemberField(typeof(int), "_originalIndex") {
                 Attributes = MemberAttributes.Private
             };