easymotion doesn't work if the character is on a folded line on the target pane

Thanks for this plugin. It works great..

One thing I noticed is that ff I am trying to move to a character on a line which is visible but folded, and use `,,s` where `<leader>=,`, `easymotion` doesn't work

Here is my configuration:

```
nmap <leader><leader>s <Plug>(easymotion-overwin-f)
```
