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/engrave.c

@@ -249,7 +249,7 @@ ceiling(int x, int y)
 }
 
 struct engr *
-engr_at(xchar x, xchar y)
+engr_at(coordxy x, coordxy y)
 {
     register struct engr *ep = head_engr;
 
@@ -269,7 +269,7 @@ engr_at(xchar x, xchar y)
  * present if it is intact and is the entire content of the engraving.
  */
 boolean
-sengr_at(const char *s, xchar x, xchar y, boolean strict)
+sengr_at(const char *s, coordxy x, coordxy y, boolean strict)
 {
     register struct engr *ep = engr_at(x, y);
 
@@ -288,7 +288,7 @@ u_wipe_engr(int cnt)
 }
 
 void
-wipe_engr_at(xchar x, xchar y, xchar cnt, boolean magical)
+wipe_engr_at(coordxy x, coordxy y, xint16 cnt, boolean magical)
 {
     register struct engr *ep = engr_at(x, y);
 
@@ -384,7 +384,7 @@ read_engr_at(int x, int y)
 }
 
 void
-make_engr_at(int x, int y, const char *s, long e_time, xchar e_type)
+make_engr_at(int x, int y, const char *s, long e_time, xint16 e_type)
 {
     struct engr *ep;
     unsigned smem = Strlen(s) + 1;
@@ -524,8 +524,8 @@ doengrave(void)
     boolean ptext = TRUE;     /* TRUE if we must prompt for engrave text */
     boolean teleengr = FALSE; /* TRUE if we move the old engraving */
     boolean zapwand = FALSE;  /* TRUE if we remove a wand charge */
-    xchar type = DUST;        /* Type of engraving made */
-    xchar oetype = 0;         /* will be set to type of current engraving */
+    xint16 type = DUST;       /* Type of engraving made */
+    xint16 oetype = 0;        /* will be set to type of current engraving */
     char buf[BUFSZ];          /* Buffer for final/poly engraving text */
     char ebuf[BUFSZ];         /* Buffer for initial engraving text */
     char fbuf[BUFSZ];         /* Buffer for "your fingers" */
@@ -703,7 +703,7 @@ doengrave(void)
             case WAN_POLYMORPH:
                 if (oep) {
                     if (!Blind) {
-                        type = (xchar) 0; /* random */
+                        type = (xint16) 0; /* random */
                         (void) random_engraving(buf);
                     } else {
                         /* keep the same type so that feels don't