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

[Juri Linkov]

> As a matter of fact, we do have to override the users' customizations
> here just as Juri suggested earlier.  Suppose a user has set
> `split-window-preferred-function' to the standard option "horizontally"
> which always splits a window horizontally.  Then `dired-pop-to-buffer'
> simply cannot get a vertical split when it calls the original
> `split-window-preferred-function'.

Thank you!  Could you also fix Proced and Calendar?

-- 
Juri Linkov
http://www.jurta.org/emacs/