(toplevel): Include pwd.h.

(toplevel): Include pwd.h.
(struct score_entry): Add username field.
(push_score): Use it.
(get_user_id): New function.
(main): Don't malloc excessively.
(main): Use username field.
(read_score): Read it.
(push_score): Handle it.
(write_scores) Write it.
(read_score): Handle arbitrary length data.