make unchecking most checkboxes a less painful process

Problem/Motivation

When configuring workbench_access for menus, if you have a really large menu or a lot of menus, you have to un-check a LOT Of boxes if you only need a few levels of editorial access.

Proposed resolution

It would be nice to have an "uncheck all" jQuery feature that would allow unchecking all boxes in a menu. The check all module provided something similar in Drupal 6, but it looks like this interface pattern might already be in core, maybe we can leverage that instead.