gpg: New option --quick-update-pref.
* g10/gpg.c (aQuickUpdatePref): New. (opts): Add --quick-update-pref. (main): Implement. * g10/keyedit.c (keyedit_quick_update_pref): New. (menu_set_preferences): Add arg 'unattended' and adjust caller.
This new quick command is in particular useful to update existing keys
so that they can be used with OCB mode.