ethumb: automagically orient thumbnails based on:

 ethumb: automagically orient thumbnails based on:
 - metadata contained in files (EXIF only currently) - default active;
 - orientation given by the caller against pixel data orientation.
 Code is based on els_icon.

 Next is to add that through dbus.

 Open question: if orientation is specified, do we need to save the thumbnail in a different folder?

git-svn-id: https://svn.enlightenment.org/svn/e/trunk/ethumb@52465 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33