src/utils.c: Add a status_ask_choice() function

This function allows the user to choose between various alternatives,
each one being associated to a given key.

This will allow a great deal of factorisation, which will make it
easier to handle special events (like resizing, user escape...) in an
uniform manner.

The cool part of the approach taken here is that it allows full i18n
(i.e. the key bound to an alternative can be different depending on
the language), at the expense of a somewhat less readable code on the
caller side.

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

src/calcurse.h

@@ -896,6 +896,7 @@ void         fatalbox (const char *);
 void         warnbox (const char *);
 void         status_mesg (const char *, const char *);
 void         status_mesg_yesno (const char *);
+int          status_ask_choice (const char *, const char[], int);
 void         erase_window_part (WINDOW *, int, int, int, int);
 WINDOW      *popup (int, int, int, int, const char *, const char *, int);
 void         print_in_middle (WINDOW *, int, int, int, const char *);