I'm interested in using Aperture to manage my very large photo library. I may not want to use Aperture forever however. So, in the future, if I want to migrate away from Aperture, how do you get your entire photo library out of Aperture? 1) Do you have to "export" all photos? 2) Can you retain your original folder structure? 3) Is there a way to browse to the actual photo files when using Aperture? Or are they completely "locked up" within Aperture?