整理代码结构，支持Package Manager添加

Demo/Runtime/Demo_PieChart.cs

@@ -0,0 +1,46 @@
+/******************************************/
+/*                                        */
+/*     Copyright (c) 2018 monitor1394     */
+/*     https://github.com/monitor1394     */
+/*                                        */
+/******************************************/
+
+using UnityEngine;
+
+namespace XCharts
+{
+    [DisallowMultipleComponent]
+    [ExecuteInEditMode]
+    [RequireComponent(typeof(PieChart))]
+    public class Demo_PieChart : MonoBehaviour
+    {
+        private PieChart chart;
+        private float time;
+        private int count = 0;
+
+        private void Awake()
+        {
+            chart = transform.GetComponent<PieChart>();
+            chart.ClearData();
+        }
+
+        private void Update()
+        {
+            time += Time.deltaTime;
+            if (time > 1)
+            {
+                time = 0;
+                if (count < 5)
+                {
+                    chart.AddData(0, Random.Range(10, 100), "time" + count);
+                }
+                else
+                {
+                    int index = count % 5;
+                    chart.UpdateData(0, Random.Range(10, 100), index);
+                }
+                count++;
+            }
+        }
+    }
+}