将Spline移出Plugin，以调整SplineRenderer的OnWillCameraRender

Assets/Dreamteck/Utilities/Singleton.cs

@@ -0,0 +1,21 @@
+namespace Dreamteck
+{
+    using System.Linq;
+    using UnityEngine;
+
+    public class Singleton<T> : PrivateSingleton<T> where T : Component
+    {
+        public static T instance
+        {
+            get
+            {
+                if (_instance == null)
+                {
+                    _instance = Object.FindObjectsOfType<T>().FirstOrDefault();
+                }
+
+                return _instance;
+            }
+        }
+    }
+}