* scd/app-nks.c (struct fid_cache_s): Add field 'algo'.
(keygripstr_from_pk_file): Add arg 'r_algo' to return the algo.
(find_fid_by_keyref): Ditto.
(get_dispserialno): New.
(make_prompt): New.
(verify_pin): Provide better prompts.
(do_decipher): Support ECDH.
(parse_pwidstr): Add hack tospecify any pwid..
(do_change_pin): Support Signature Card V2.0 (NKS15) style NullPIN.
Provide a better prompt.