请问如何用正则表达式批量替换画板和图层名称？
#### Please tell us your OS and Sketch version when create issues.

- [x] Make sure you are using the latest version of [WeSketch](https://github.com/weixin/WeSketch)
- [x] OS Version: `macOS (10.12.x)`
- [x] Sketch Version: `v44.1+`

#### Issues below
OS Version: `macOS (10.13.6)`
Sketch Version: `v52.2`
如下两图，我想把图层名的空格替换成下划线，这样写不对吗？请问正确的写法是怎样？谢谢了
![image](https://user-images.githubusercontent.com/3748730/48990116-1bcb4800-f168-11e8-8353-aca5dcc5aca2.png)
![image](https://user-images.githubusercontent.com/3748730/48990135-3a314380-f168-11e8-9c57-5ad9b58440d7.png)

