Initial commit
working dl_list class
Minor cosmectic change
Add dl_ordered_list

Remove dl_list::insert_middle()
Add dl_list::insert()
Fix ctl::dl_list::insert()

ctl::dl_list::insert() now works for beginning and end values.
Implement ctl::dl_ordered_list::add()
Operational ctl::stack and stl::queue
Add variable order to ctl::dl_ordered_list
Cosmetic changes
Add ctl::ordered_stack and ctl::priority_queue

Enable descending order in all ordered list types
Merge from assignment 2