undo & redo for file info

sample/vars/declare-vars.json

@@ -3,7 +3,9 @@
   "desc": "",
   "firstid": 1,
   "export": true,
-  "import": ["vars/declare-core.json"],
+  "import": [
+    "vars/declare-core.json"
+  ],
   "declvar": [
     {
       "name": "owner",
@@ -17,5 +19,6 @@
   "root": {
     "id": 1,
     "name": "Sequence"
-  }
-}
+  },
+  "group": []
+}

sample/vars/test-vars.json

@@ -18,10 +18,6 @@
     {
       "name": "target1",
       "desc": "其它目标"
-    },
-    {
-      "name": "test",
-      "desc": "测试"
     }
   ],
   "root": {