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/winami.h

@@ -37,13 +37,13 @@ struct amii_menu {
  * tty-style windows also, then things will need to change. */
 /* per-window data */
 struct amii_WinDesc {
-    xchar type; /* type of window */
+    xint16 type; /* type of window */
     struct amii_menu menu;
     boolean active; /* true if window is active */
     boolean wasup;  /* true if menu/text window was already open */
     short
         disprows; /* Rows displayed so far (used for paging in message win) */
-    xchar offx, offy;         /* offset from topleft of display */
+    coordxy offx, offy;         /* offset from topleft of display */
     short vwx, vwy, vcx, vcy; /* View cursor location */
     short rows, cols;         /* dimensions */
     short curx, cury;         /* current cursor position */