* command-ssh.c (ssh_handler_request_identities)
(ssh_handler_sign_request, ssh_handler_add_identity)
(ssh_handler_remove_identity, ssh_handler_remove_all_identities)
(ssh_handler_lock, ssh_handler_unlock): Changed to return an error
code instead of a boolean.
(ssh_request_process): Changed to return a boolean instead of an
error; adjust caller.
(ssh_request_handle_t): Adjusted type.
(ssh_request_spec): New member: identifier.
(REQUEST_SPEC_DEFINE): New macro; use it for initialization of
request_specs[].
(ssh_request_process): In debugging mode, log identifier of
handler to execute.
(start_command_handler_ssh): Moved most of the stream handling
code ...
(ssh_request_process): ... here.
