* scd/app-p15.c: Add a couple of oid constants.
(struct cdf_object_s): Replace fields image and imagelen by cert.
(struct prkdf_object_s): Add extusage flags
(send_keypairinfo): Use them.
(cdf_object_from_certid): Factor parts out to ...
(cdf_object_from_objid): new function.
(read_ef_prkdf): Move info printing to ...
(read_p15_info): here.  Fill the extusage flags.
(readcert_by_cdf): Cache the ksba cert object instead of the binary
cert.
* scd/app.c (select_additional_application): Fix a log_debug call.
(scd_update_reader_status_file): Ditto.