[KPhotoAlbum] Another try at viewer size manipulation

[Robert L Krawitz]

This patch contains everything I did yesterday plus the following:

1) Ability to scale to less than full screen.  This means that
   displaying pixel for pixel will always display pixel for pixel, in
   addition to the ability to zoom out beyond that point.

2) A new "standard size" setting, which can be one of three things:

   * Full screen (the default, as today)

   * Natural size (i. e. pixel for pixel)

   * Natural size if possible (pixel for pixel if it would fit,
     otherwise full screen).

   This is on the `/' key.  It might be nice for some kind of sticky
   setting such that each image is loaded at the last specified
   scaling.

There may be opportunities for optimization here; there might be too
many reloads going on, for example.  This is only partially tested,
also.  Comments please.

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lpf at uunet.uu.net
Project lead for Gutenprint   --    http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton