- Breadcrumb::build_from_item becomes Breadcrumb::array_from_item_parents
- Eliminate Breadcrumb::$id -- it's no longer necessary
- Fold Breadcrumb::generate_show_query_strings into Breadcrumb::array_from_item_parents
- Create Breadcrumb::set_first() and Breadcrumb::set_last()
- Breadcrumb::build_from_list goes away, we just use arrays for this
- Change Search_Controller and Tag_Controller to just create an array
of Breadcrumb instances with the first/last marked appropriately
- Breadcrumb_Test loses a bunch of complexity.