agent is to be used. Noted by Ingo Kl�cker.
(agent_get_passphrase): Inhibit caching when we have no
fingerprint. This is required for key generation as well as for
symmetric only encryption.
* passphrase .c (agent_get_passphrase): New arg CANCELED.
(passphrase_to_dek): Ditto. Passed to above. Changed all
callers to pass NULL.
* seckey-cert.c (do_check): New arg CANCELED.
(check_secret_key): Terminate loop when canceled.
* keyedit.c (change_passphrase): Pass ERRTEXT untranslated to
passphrase_to_dek and translate where appropriate.
* seckey-cert.c (check_secret_key): Ditto.
* keygen.c (ask_passphrase): Ditto.
* passphrase.c (agent_get_passphrase): Translate the TRYAGAIN_TEXT.
Switch the codeset to utf-8.
