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

include/hack.h

@@ -170,13 +170,13 @@ typedef union str_or_len {
 /* lev_region from sp_lev.h */
 typedef struct {
     struct {
-        xchar x1, y1, x2, y2;
+        coordxy x1, y1, x2, y2;
     } inarea;
     struct {
-        xchar x1, y1, x2, y2;
+        coordxy x1, y1, x2, y2;
     } delarea;
     boolean in_islev, del_islev;
-    xchar rtype, padding;
+    coordxy rtype, padding;
     Str_or_Len rname;
 } lev_region;
 
@@ -251,9 +251,9 @@ struct sortloot_item {
     char *str; /* result of loot_xname(obj) in some cases, otherwise null */
     int indx; /* signed int, because sortloot()'s qsort comparison routine
                  assumes (a->indx - b->indx) might yield a negative result */
-    xchar orderclass; /* order rather than object class; 0 => not yet init'd */
-    xchar subclass; /* subclass for some classes */
-    xchar disco; /* discovery status */
+    xint16 orderclass; /* order rather than object class; 0 => not yet init'd */
+    xint16 subclass; /* subclass for some classes */
+    xint16 disco; /* discovery status */
 };
 typedef struct sortloot_item Loot;