scd:openpgp: Allow auto-changing of the key attributes in genkey.
* scd/app-openpgp.c (struct app_local_s): Add field keyalgo. (parse_algorithm_attribute): Store the new keyalgo field. (change_keyattr): Change info message. (change_keyattr_from_string): Rewrite to also accept a keyref and a keyalgo string. (do_genkey): Change the keyattr if a keyalgo string is given.
Having this feature makes it easier to use OpenPGP cards in a similar
way to other cards. Note that the explicit changing via SETATTR is
still supported.
- Signed-off-by: Werner Koch <wk@gnupg.org>