redo achievement tracking

Instead of an assortment of bits, assign numeric indices to the
potential achievements and keep an array of those in the order they
were attained.  So disclosure might show the same subset occurring
differently in different games depending on the player's actions.
The encoded field in xlogfile doesn't care about that and remains
the same.

Modifies 'struct u', so EDITLEVEL has been incremented and existing
save files are invalidated.

src/spell.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	spell.c	$NHDT-Date: 1546565814 2019/01/04 01:36:54 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.88 $ */
+/* NetHack 3.6	spell.c	$NHDT-Date: 1581322667 2020/02/10 08:17:47 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.102 $ */
 /*      Copyright (c) M. Stephenson 1988                          */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -259,6 +259,7 @@ struct obj *book2;
             /* successful invocation */
             mkinvokearea();
             u.uevent.invoked = 1;
+            record_achievement(ACH_INVK);
             /* in case you haven't killed the Wizard yet, behave as if
                you just did */
             u.uevent.udemigod = 1; /* wizdead() */