Migrate to new tribufu project structure

Source/Tribufu.Serialization/ULongStringConverter.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Tribufu. All Rights Reserved.
+// SPDX-License-Identifier: MIT
+
+using Newtonsoft.Json;
+using System;
+
+namespace Tribufu.Serialization
+{
+    public class ULongStringConverter : JsonConverter<ulong>
+    {
+        public override ulong ReadJson(JsonReader reader, Type objectType, ulong existingValue, bool hasExistingValue, JsonSerializer serializer)
+        {
+            if (reader.TokenType == JsonToken.String && ulong.TryParse(reader.Value?.ToString(), out var result))
+            {
+                return result;
+            }
+
+            if (reader.TokenType == JsonToken.Integer)
+            {
+                return Convert.ToUInt64(reader.Value);
+            }
+
+            throw new JsonSerializationException($"Unexpected token {reader.TokenType} when parsing ulong.");
+        }
+
+        public override void WriteJson(JsonWriter writer, ulong value, JsonSerializer serializer)
+        {
+            writer.WriteValue(value.ToString());
+        }
+    }
+}