Move unnecessary stuff out of update_image():

Situation: On every call it was checked if it's an animation, picture or if this stuff was already checked.
Normally that should be checked just once. If move_index() is used. Only time self.pixbufOriginal gets a completly new file.
So the check if the loaded animation is really an animation or just a static image is moved to move_index().
In update_image() just remains the check for a pixbuf or pixbuf animation as they're differenly set.
No zoom with PixbufAnimation

pygobject doesn't support scaling with a PixbufAnimation. So if checks included to ignore zoom_delta and zoom_to if it's an animation.
0.5.2
Optimize deletion process

Problem: If at /tmp/pim-trash is already a file with that name, the actual file won't be moved to that location, but will be removed from self.paths + error message.

Solution: Iterate as long as necessary, until the file in /tmp/pim-trash can be renamed, then move the new/current file to pim-trash.
Pro:
 * No extra module
 * No name collision
Con:
 * Not so clean and easy as the other solution
 * Dunno how much time it will need, when there is a large number of name duplicates