scd: Add --advanced option for READKEY.
* scd/command.c (cmd_readkey) : Support ADVANCED arg. * scd/app.c (app_readcert): Add ADVANCED arg. * scd/app-openpgp.c (do_readkey): Implement ADVANCED arg. * scd/app-nks.c (do_readkey): Error return with GPG_ERR_NOT_SUPPORTED.
"SCD READKEY --advanced OPENPGP.3" returns key in advanced format.
With this suport, poldi-ctrl will be no longer needed.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>