从Serein.Library分离了WebSocket/Modbus；新增了Json门户类，用于未来的Http、WebSocket、Mqtt、gRPC、QUIC扩展。

Library/Api/ISereinFlow.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Serein.Library.Api
+{
+    /// <summary>
+    /// 空接口
+    /// </summary>
+    public interface ISereinFlow
+    {
+
+    }
+
+}