Drag-and-drop content ordering via weight module

This is a views integration for the weight module.

It includes a Weight field which displays the weight, a Weight sort (which allows you to order by Weight ASC which I think is more intuitive but is the same as ordering by Sticky DESC), and best of all a new style plugin called 'Weight Changer'.

This lets you can set up a view using the 'Weight Changer' style and include the Weight field and Sort by Weight ASC. The resulting view is a form displayed as a table with drag and drop for updating the weights.

This patch was sponsored by Bluecadet Interactive and has now been committed to the HEAD version of weight module.