1. Updates the basket groups interface so that it doesn't rely on YUI to move baskets in and out of groups.
2. Removes all YUI assets and many long-obsolete references to YUI-related classes and IDs.
For basket groups, you no longer need to drag and drop baskets between columns (which could be a bit fiddly).
The basket group form is now in one column and ungrouped baskets in another. Baskets are listed in sortable tables, and using 'Add to group' and 'Remove' buttons lets you add and remove baskets from the group.