Adding choice for "fit to window" for picture disp

Here is a patch for gallery 1.3.4 that lets users choose between "normal", "full" and "fit to window" (new choice) when viewing pictures, instead of the previous "normal/full"-only choice.

This lets users with a good bandwidth connection (or LAN users) view pictures in full screen resized version, which is in my opinion often more useful than displaying the full sized picture that is usually larger than the screen. Of course the option to view the full-sized version is still there.

Please let me know if you like this, I'm also thinking of releasing a patch for a full-screen slideshow (in a popup fullscreen window).

The attachement is a patch against view_photo.php.

Feedback welcome!