Reimplement the TreeSet class by adding to each node two links: next and previous, representing the previous and next item that would be obtained in an inorder tree traversal. Also add header and tail...

Reimplement the TreeSet class by adding to each node two links: next and previous, representing the previous and next item that would be obtained in an inorder tree traversal. Also add header and tail nodes to avoid special cases for the minimum and maximum item. This simplifies the iterator implementation considerably, but requires revisions to the mutators.