Note, that I have not yet achieved to generate a cert with the
subjectAltName using OpenSSL. It seems that openssl requires the
email address to be part of the subject DN (subjectAltName=email:copy)
but this is something we don't want to do.
* server.c (cmd_genkey): New.
* certreqgen.c: New. The parameter handling code has been taken
from gnupg/g10/keygen.c version 1.0.6.
* call-agent.c (gpgsm_agent_genkey): New.