Feature request: hotkeys for navigating between pinned files

[saaguero]

I'm not sure if this is possible yet, in case is not, here is what I'm proposing:

1. Have a way to define hotkeys to jump between the pinned files, it could be the top 5 or a custom 'N'.
2. That is, we can have either by default or a custom bindings like

nnoremap <silent> <leader>f1 :PoplarPin1<cr>
nnoremap <silent> <leader>f2 :PoplarPin2<cr>
...
nnoremap <silent> <leader>f5 :PoplarPin5<cr>

The idea is to reduce the extra step of checking the Poplar popup and navigating to the desire pinned file.

[ycm]

This is possible without too much work.

This is how the logic is handled currently, via the pinned items menu:

https://github.com/ycm/poplar.vim/blob/master/autoload/pinwindow.vim#L248-L258

To add a feature like this you'd add the relevant logic in autoload/poplar.vim, essentially how _TryOpenFile() works in pinwindow.vim, and just expose the binding in plugin/poplar.vim.

I can do this but am constrained on bandwidth. feel free to add a PR