* scd/app-piv.c (parse_pin_keyref): New.
(get_chv_status): New.
(do_getattr): Add name CHV-STATUS.
(verify_pin): Add arg keyref to support other PINs.
(do_change_pin): New.  Right now limited to --clear.
(do_check_pin): New.
(app_select_piv): Register new commands.