* agent/command.c (cmd_genkey): Add option --timestamp.
(cmd_import_key): Ditto.
* agent/genkey.c (store_key): Add arg timestamp and change callers.
(agent_genkey): Ditto.
* agent/findkey.c (write_extended_private_key): Add args timestamp and
newkey to write a Created line.
(agent_write_private_key): Add arg timestamp.
(agent_write_shadow_key): Ditto.
* agent/protect-tool.c (agent_write_private_key): Ditto as dummy arg.