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/flag.h

@@ -87,6 +87,7 @@ struct flag {
     int pile_limit;    /* controls feedback when walking over objects */
     char discosort;    /* order of dodiscovery/doclassdisco output: o,s,c,a */
     char sortloot; /* 'n'=none, 'l'=loot (pickup), 'f'=full ('l'+invent) */
+    uchar vanq_sortmode; /* [uint_8] order of vanquished monsters: 0..7 */
     char inv_order[MAXOCLASSES];
     char pickup_types[MAXOCLASSES];
 #define NUM_DISCLOSURE_OPTIONS 6 /* i,a,v,g,c,o (decl.c) */