FINALLY update the number of copies of a book correctly (doesn't delete checked-in copies and deletes book if all copies are deleted); display number of copies available to check out
show a patron their checkout history and the due date of one of their checked-out books
delete a patron from the database; delete inactive checkouts if book, copy, or patron is deleted
WIP on UI; still need to report overdue books, count checkouts, and count overdue books; merging with master to push to github