better interface for sorting pages

[mark_heydon]

It is very tedious to re-sort pages in a .pbix file, particularly if you have say 20 pages and the new page you've just created is page 20 and you want it to be page 2 or 3 - you have to drag it to the left hand end, move across a pane, drag it to the new end, and so on. It would be nice to have a thumbnail view of the pages on a single screen, a little like the slide sorter view in PowerPoint, to reorder the pages.