toolbar拓展布局自适应优化，以及场景切换分组：初始场景、默认包、其他场景。

UnityProject/Assets/Editor/ToolbarExtender/UnityToolbarExtenderLeft/UnityToolbarExtenderLeft.cs

@@ -0,0 +1,16 @@
+using UnityEditor;
+using UnityToolbarExtender;
+
+namespace TEngine
+{
+    [InitializeOnLoad]
+    public partial class UnityToolbarExtenderLeft
+    {
+        static UnityToolbarExtenderLeft()
+        {
+            ToolbarExtender.LeftToolbarGUI.Add(OnToolbarGUI_SceneLauncher);
+            EditorApplication.playModeStateChanged += OnPlayModeStateChanged;
+            EditorApplication.quitting += OnEditorQuit;
+        }
+    }
+}