new 'sortvanquished' option

Allow the preferred sort order for the vanquished monsters list to
be specified in the run-time config file
|OPTIONS=sortvanquished:X
where X is t, d, a, c, n, or z.  It can also be set to 'A' or 'C'
but those aren't documented and aren't offered as choices when
setting the value interactively, which can be done via 'm O' or by
using 'm #vanquished'.

Guidebook.mn has been updated but Guidebook.tex is lagging again.

include/optlist.h

@@ -537,6 +537,9 @@ static int optfn_##a(int, int, boolean, char *, char *);
                 "sort object selection lists by description")
     NHOPTB(sortpack, Advanced, 0, opt_out, set_in_game,
                 On, Yes, No, No, NoAlias, &flags.sortpack)
+    NHOPTC(sortvanquished, Advanced, 0, opt_in, set_in_game,
+                Yes, Yes, No, Yes, NoAlias,
+                "preferred order when displaying vanquished monsters")
     NHOPTB(sparkle, Map, 0, opt_out, set_in_game,
                 On, Yes, No, No, NoAlias, &flags.sparkle)
     NHOPTB(splash_screen, Advanced, 0, opt_out, set_in_config,