* scd/scdaemon.h (DBG_APP_VALUE, DBG_APP): New.
* scd/scdaemon.c (debug_flags): Add "app".
* scd/app.c (xstrapptype): New.
(app_readcert, app_readkey, app_getattr): Add debug output.
(app_setattr, app_sign, app_auth): Ditto.
(app_writecert, app_writekey, app_change_pin): Ditto.
(app_check_pin): Ditto.