Feature(multiple pop): now we can pop multipe scenes with Actions.pop

src/Reducer.js

@@ -63,11 +63,21 @@ function inject(state, action, props, scenes) {
       if (state.index === 0) {
         return state;
       }
+
+      let popNum = 1
+      if (action.data) {
+        assert(typeof(action.data) === 'number', 'The data is the number of scenes you want to pop, it must be Number')
+        popNum = action.data
+        assert(popNum % 1 === 0, 'The data is the number of scenes you want to pop, it must be integer.')
+        assert(popNum > 1, 'The data is the number of scenes you want to pop, it must be bigger than 1.')
+        assert(popNum < state.children.length, "The data is the number of scenes you want to pop, it must be smaller than scenes stack's length.")
+      }
+
       return {
         ...state,
-        index: state.index - 1,
-        from: state.children[state.children.length - 1],
-        children: state.children.slice(0, -1),
+        index: state.index - popNum,
+        from: state.children[state.children.length - popNum],
+        children: state.children.slice(0, -1 * popNum),
       };
     case REFRESH_ACTION:
       return props.base ?