New Photo Gallery, Reordered items in backend, Renamed documents to Pages

New feature: Photo Gallery - create a gallery and upload photos to it
which are automatically resized and saved in 3 versions (thumbnail,
small and original). Display the gallery in the front end using
prettyphoto. A few minor changes to the order of items in the backend
menu.
Planning to make it possible to add galleries to pages and display them
in the frontend.