scd: New commands SWITCHCARD and SWITCHAPP.
* scd/app.c: Include membuf.h. (app_switch_current_card): New. (send_card_and_app_list): Factor code out to ... (send_serialno_and_app_status): new. (app_send_card_list): New. (app_send_active_apps): New. (app_switch_active_app): New. * scd/command.c (cmd_switchcard): New. (cmd_switchapp): New. (register_commands): Register new commands. (cmd_getinfo): New sub-commands "active_apps" and "all_active_apps".
These new commands allow to switch between known cards and are in
particular useful for the gpg-card tool.
- Signed-off-by: Werner Koch <email@example.com>