change xchar to other typedefs

One of the drivers of this change was that screen coordinates require a
type that can hold values greater than 127. Parameters to the window
port routines require a large type in order to be able to have values
a fair bit larger than COLNO and ROWNO passed to them, particularly for
their use to the right of the map window.

This splits the uses of xchar into 3 different situations, and adjusts
their type and size:

                        xchar
                          |
               -----------------------
               |          |          |
            coordxy     xint16     xint8

coordxy: Actual x or y coordinates for various things (moved to 16-bits).

xint16:  Same data size as coordxy, but for non-coordinate use (16-bits).

xint8:   There are only a few use cases initially, where it was very
         plain to see that the variable could remain as 8-bits, rather
         than be bumped to 16-bits.  There are probably more such cases
         that could be changed after additional review.

Note: This first changed all xchar variables to coordxy. Some were
reviewed and got changed to xint16 or xint8 when it became apparent that
their usage was not for coordinates.

This increments EDITLEVEL in patchlevel.h

src/dog.c

@@ -66,7 +66,7 @@ pet_type(void)
 }
 
 struct monst *
-make_familiar(struct obj *otmp, xchar x, xchar y, boolean quietly)
+make_familiar(struct obj *otmp, coordxy x, coordxy y, boolean quietly)
 {
     struct permonst *pm;
     struct monst *mtmp = 0;
@@ -302,7 +302,8 @@ void
 mon_arrive(struct monst *mtmp, boolean with_you)
 {
     struct trap *t;
-    xchar xlocale, ylocale, xyloc, xyflags, wander;
+    coordxy xlocale, ylocale, xyloc, xyflags;
+    xint16 wander;
     int num_segs;
     boolean failed_to_place = FALSE;
     stairway *stway;
@@ -366,7 +367,7 @@ mon_arrive(struct monst *mtmp, boolean with_you)
         mtmp->mlstmv = g.moves - 1L;
 
         /* let monster move a bit on new level (see placement code below) */
-        wander = (xchar) min(nmv, 8);
+        wander = (xint16) min(nmv, 8);
     } else
         wander = 0;
 
@@ -716,12 +717,13 @@ keepdogs(
 void
 migrate_to_level(
     struct monst *mtmp,
-    xchar tolev, /* destination level */
-    xchar xyloc, /* MIGR_xxx destination xy location: */
+    xint16 tolev, /* destination level */
+    xint16 xyloc, /* MIGR_xxx destination xy location: */
     coord *cc)   /* optional destination coordinates */
 {
     d_level new_lev;
-    xchar xyflags, mx = mtmp->mx, my = mtmp->my; /* <mx,my> needed below */
+    coordxy xyflags;
+    coordxy mx = mtmp->mx, my = mtmp->my; /* <mx,my> needed below */
     int num_segs; /* count of worm segments */
 
     if (mtmp->mleashed) {
@@ -735,8 +737,8 @@ migrate_to_level(
     relmon(mtmp, &g.migrating_mons); /* mtmp->mx,my retain their value */
     mtmp->mstate |= MON_MIGRATING;
 
-    new_lev.dnum = ledger_to_dnum((xchar) tolev);
-    new_lev.dlevel = ledger_to_dlev((xchar) tolev);
+    new_lev.dnum = ledger_to_dnum((xint16) tolev);
+    new_lev.dlevel = ledger_to_dlev((xint16) tolev);
     /* overload mtmp->[mx,my], mtmp->[mux,muy], and mtmp->mtrack[] as
        destination codes */
     xyflags = (depth(&new_lev) < depth(&u.uz)); /* 1 => up */