重写脚本解释器的实现，提高其可读性。

Serein.Script/Node/FlowControl/WhileNode.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Serein.Script.Node.FlowControl
+{
+    /// <summary>
+    /// 循环条件节点
+    /// </summary>
+    public class WhileNode : ASTNode
+    {
+        /// <summary>
+        /// 循环条件值来源
+        /// </summary>
+        public ASTNode Condition { get; }
+
+        /// <summary>
+        /// 循环中语句块
+        /// </summary>
+        public List<ASTNode> Body { get; }
+        public WhileNode(ASTNode condition, List<ASTNode> body) => (Condition, Body) = (condition, body);
+    }
+
+}