[Proposal] Add the possibility to pin folders

[cristianvasquez]

First of all, thanks for this great plugin!

Sometimes we work a lot between two folders. It would be awesome to be able to pin them, in the same way that you can pin notes.

[jvdevlab]

Something along the lines of a toolbar with icons for pinned folders would be cool. It will allow to jump around quickly from one branch to another in a large folder structure.