优化：切换结构时重置画布缩放，以修复当存在缩放时切换结构后第一次拖动会突变的问题

simple-mind-map/index.js

@@ -281,6 +281,7 @@ class MindMap {
       layout = CONSTANTS.LAYOUT.LOGICAL_STRUCTURE
     }
     this.opt.layout = layout
+    this.view.reset()
     this.renderer.setLayout()
     this.render()
   }

simple-mind-map/src/View.js

@@ -167,10 +167,14 @@ class View {
 
   //  恢复
   reset() {
+    let scaleChange = this.scale !== 1
     this.scale = 1
     this.x = 0
     this.y = 0
     this.transform()
+    if (scaleChange) {
+      this.mindMap.emit('scale', this.scale)
+    }
   }
 
   //  缩小