add 增加logicflow流程图预览

src/components/Process/js/start.js

@@ -0,0 +1,16 @@
+import { CircleNode, CircleNodeModel } from '@logicflow/core';
+
+class StartModel extends CircleNodeModel {
+  initNodeData(data) {
+    super.initNodeData(data);
+    this.r = 20;
+  }
+}
+
+class StartView extends CircleNode {}
+
+export default {
+  type: 'start',
+  model: StartModel,
+  view: StartView
+};