hero_seq

'moves' is actually turns and there hasn't been any straightforward
way to track actual hero moves.  Add hero_seq for that.  It isn't a
counter but is distinct each time the hero makes a move.  I wanted
it for curses ^P support but so far use it for checking stethoscope
usage and for shopkeeper behavior when items in a shop are broken by
the hero.

Increment EDITLEVEL due to change in save file contents.

include/decl.h

@@ -822,6 +822,8 @@ struct instance_globals {
     struct mkroom *subrooms;
     dlevel_t level; /* level map */
     long moves; /* turn counter */
+    long hero_seq; /* 'moves*8 + n' where n is updated each hero move during
+                    * the current turn */
     long wailmsg;
     struct obj *migrating_objs; /* objects moving to another dungeon level */
     struct obj *billobjs; /* objects not yet paid for */