Support for coming back from link jumps

[lsponzoni]

So I've been reading a book that is full of footnotes. The footnotes themselves link to appendices. And appendices themselves have links to other parts of the book.
In such kind of book, as Quality of Life improvement to the reader, is keeping a mark for the return of each jump, as the current code allow with the ' mark, but that allows only for one jump. The backspace could be bound to this move. It is similar to what Ctrl + O does on vim.

[097115]

Would be great if we could somehow select footnotes with the keyboard, too.

E.g., to have a dedicated key to go the first available footnote counting from the top of the screen.