版本：2.5.1
- https://cdn.bootcdn.net/ajax/libs/jsPlumb/2.5.1/css/jsplumbtoolkit-defaults.css
- https://cdn.bootcdn.net/ajax/libs/jsPlumb/2.5.1/css/jsplumbtoolkit-defaults.min.css
- https://cdn.bootcdn.net/ajax/libs/jsPlumb/2.5.1/js/jsplumb.js
- https://cdn.bootcdn.net/ajax/libs/jsPlumb/2.5.1/js/jsplumb.min.js