add exit title preference to group and add command for setting the preference

src/ui/ui.h

@@ -300,6 +300,7 @@ void cons_time_setting(void);
 void cons_mouse_setting(void);
 void cons_statuses_setting(void);
 void cons_titlebar_setting(void);
+void cons_exittitle_setting(void);
 void cons_notify_setting(void);
 void cons_show_desktop_prefs(void);
 void cons_states_setting(void);