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/mextra.h

@@ -132,7 +132,9 @@ struct eshk {
     d_level shoplevel;    /* level (& dungeon) of his shop */
     int billct;           /* no. of entries of bill[] in use */
     struct bill_x bill[BILLSZ];
-    struct bill_x *bill_p;
+    struct bill_x *bill_p;  /* &(ESHK(shkp)->bill[0]) */
+    long break_seq;         /* hero_seq value at time of object breakage */
+    boolean seq_peaceful;   /* shkp->mpeaceful at start of break_seq */
     int visitct;            /* nr of visits by most recent customer */
     char customer[PL_NSIZ]; /* most recent customer */
     char shknam[PL_NSIZ];