Sometimes convert result will be \uXXXX.

Hi, there're more and more template engine, some template engine may cause the result contain "\\uxxxx", if someone use the `gulp-native2ascii` around the template engine render action, it doesn't work possibility.


eg:
```
.pipe(N2A({reverse: false}))
.pipe(TemplateEngine.render())
.pipe(N2A({reverse: true}))
```

:D
There're some template engine will render "\\u1234" -> "\\\\u1234", so it seems to restore the string one by one.