bug#1806: dired-pop-to-buffer in wrong place

[martin rudalics]

> Actually Dired already displays that list in the Dired window itself
> when the list is too large and fills the whole window.  But it would be
> bad to replace the Dired buffer with a small list with 2-3 filename lines
> and a lot of empty lines.  So it is better to display a separate window
> near the minibuffer without empty lines using `fit-window-to-buffer'.

Reasonable.  I suppose we should try to stay in the same "column" when
frames are divided horizontally.  Any fallback we should use when a
bottom window can't be split?  Split the selected one?

martin