* app.c (app_setattr): New.
(do_getattr): New.
(do_learn_status): Reimplemented in terms of do_getattr.
* app-openpgp.c (do_change_pin): Make sure CVH1 and CHV2 are
always synced.
(verify_chv2, verify_chv3): New. Factored out common code.
(do_setattr, do_sign, do_auth, do_decipher): Change the names of
the prompts to match that we have only 2 different PINs.
(app_select_openpgp): Check whether the card enforced CHV1.
(convert_sig_counter_value): New. Factor out code from
get_sig_counter.