Version 2.1, rotation and visual centering

adds layouts with rotated images and visual centering of images. Also adds a number of further layouts

Version 2, with GUI

This release introduces a major change (and hopefully, an improvement) by providing a GUI using tkinter.
Mac users will therefore have to install a full python version.
Instead of generating the page layouts with scripts, the users choose a layout based on the number of landscape and portrait images they want to show on the page, or area on the page.
All the previous version 1 scripts are still available and useful in many situations.

First public release

This is the first release with all the main functionalities I wanted to implement.