bug#21100: 25.0.50; quit-restore-window should also retore width, not just height

[martin rudalics]

> So what you probably want is a new option `even-window-widths' (or maybe
> `even-window-sizes') which, if non-nil, does for side-by-side splits the
> same thing `even-window-heights' does for a below split.  And,
> obviously, `quit-restore-window' should be able to size it back (I have
> written this part already).

I renamed `even-window-heights' to `even-window-sizes'.  The behavior
should be now as you requested.  Please have a look.

martin