Factorize boolean user prompting.

Introduce a new `status_ask_bool()` function, and use it where
applicable.

This greatly reduces code duplication, and will allow handling special
events (resize, user escape) much more uniformely.

Signed-off-by: Baptiste Jonglez <baptiste--git@jonglez.org>
Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/apoint.c

@@ -276,8 +276,7 @@ apoint_delete (unsigned *nb_events, unsigned *nb_apoints)
 
   if (conf.confirm_delete)
     {
-      status_mesg_yesno (del_app_str);
-      if (wgetch (win[STA].p) != 'y')
+      if (status_ask_bool (del_app_str) != 1)
         {
           wins_erase_status_bar ();
           return;