建立项目版本为Unity4.6，改为5.3.4版本，运行项目报如下错误：
“BCE0004: Ambiguous reference 'preview': CameraMotionBlurEditor.preview, UnityEditor.Editor.preview.”
修改 preview 为 preview_
var preview_ : SerializedProperty;
preview_ = serObj.FindProperty ("preview");
EditorGUILayout.PropertyField (preview_, new GUIContent("Preview"));
if (preview_.boolValue)