* findkey.c (agent_write_private_key,agent_key_from_file)
(agent_key_available): Use GNUPG_PRIVATE_KEYS_DIR constant.
* gpg-agent.c (main): Use GNUPG_DEFAULT_HOMEDIR constant.
* protect-tool.c (store_private_key): New.
(import_p12_file): Store the new file if requested.
(main): New options --force and --store.
* gpg-agent.c (main): Set a global flag when runing detached.
* query.c (start_pinentry): Pass the list of FD to keep in the
child when not running detached.
* call-scd.c (start_scd): Ditto.
