优化性能，优化折线图和柱状图的大数据绘制，重构代码

Runtime/Internal/ListPool.cs

@@ -6,13 +6,24 @@
 /******************************************/
 
 using System.Collections.Generic;
+using UnityEngine;
 
 namespace XCharts
 {
     internal static class ListPool<T>
     {
-        private static readonly ObjectPool<List<T>> s_ListPool = new ObjectPool<List<T>>(null, Clear);
-        static void Clear(List<T> l) { l.Clear(); }
+        private static readonly ObjectPool<List<T>> s_ListPool = new ObjectPool<List<T>>(OnGet, OnClear);
+        static void OnGet(List<T> l)
+        {
+            if (l.Capacity < 50)
+            {
+                l.Capacity = 50;
+            }
+        }
+        static void OnClear(List<T> l)
+        {
+            l.Clear();
+        }
 
         public static List<T> Get()
         {
@@ -23,5 +34,10 @@ namespace XCharts
         {
             s_ListPool.Release(toRelease);
         }
+
+        public static void ClearAll()
+        {
+            s_ListPool.ClearAll();
+        }
     }
 }