0.2版本，重构代码，增加Editor

Scripts/Editor/PieChartEditor.cs

@@ -0,0 +1,27 @@
+using UnityEditor;
+
+namespace XCharts
+{
+    /// <summary>
+    /// Editor class used to edit UI PieChart.
+    /// </summary>
+
+    [CustomEditor(typeof(PieChart), false)]
+    public class PieChartEditor : BaseChartEditor
+    {
+        protected SerializedProperty m_Pie;
+
+        protected override void OnEnable()
+        {
+            base.OnEnable();
+            m_Target = (PieChart)target;
+            m_Pie = serializedObject.FindProperty("m_Pie");
+        }
+
+        protected override void OnEndInspectorGUI()
+        {
+            base.OnEndInspectorGUI();
+            EditorGUILayout.PropertyField(m_Pie, true);
+        }
+    }
+}