[Feature request] Fit window to page
I'm not a native English speaker but I'll try to explain what I mean as best as I can. I often find myself having to resize Zathura window manually so as the window is the right size for the document I'm viewing. In case of documents that are vertical, I'd want Zathura to take as much vertical space of my screen as possible and just enough horizontal space to fit the page entirely but not create black stripes on both sides of the screen and wasting screen space.
And this is what I would want to have a key binding for- automatically resizing the window so it only uses as much space as it's needed to display a page as big as possible (of course in this case I resized the window manually):