修改了http服务器无法正确处理post请求入参；添加了modbus tcp客户端支持。

Library/Network/Modbus/ModbusTcpRequest.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Serein.Library.Network.Modbus
+{
+    /// <summary>
+    /// Modbus TCP 请求实体
+    /// </summary>
+    public class ModbusTcpRequest
+    {
+        /// <summary>
+        /// 事务ID
+        /// </summary>
+        public ushort TransactionId { get; set; }
+        /// <summary>
+        /// 功能码
+        /// </summary>
+        public ModbusFunctionCode FunctionCode { get; set; }
+        /// <summary>
+        /// PDU 数据
+        /// </summary>
+        public byte[] PDU { get; set; }
+        /// <summary>
+        /// 请求的完成源，用于异步等待响应
+        /// </summary>
+        public TaskCompletionSource<byte[]> Completion { get; set; }
+    }
+
+}