(strtox, strtoy): New. Use it instead of inputxy() to avoid the

double-remainder problem: x-coordinate SHRT_MAX+1 is truncated to 0 by
cast to coord, then converted by xabs().  This is wrong unless WORLD_X
divides SHRT_MAX+1.
(sarg_xy, sarg_getrange, sarg_range): Use them.
(inputxy): No longer used, remove.

(sarg_type): Use NS_UNDEF instead of 0.

(sarg_list): Change confusing loop control.  Properly diagnose
overlong lists; used to silently ignore list tail and return MAX+1,
which made a later snxtitem_list() fail.

(atoip): No longer used, remove.  Parsing was broken anyway.

(sarg_type, sarg_xy, sarg_area, sarg_range, sarg_list, sarg_getrange):
Use plain char * instead of s_char *.

src/lib/common/xy.c

@@ -32,13 +32,14 @@
  */
 
 #include <ctype.h>
+#include <errno.h>
 #include <stdarg.h>
+#include <stdio.h>
 #include "misc.h"
 #include "xy.h"
 #include "nat.h"
 #include "sect.h"
 #include "file.h"
-#include <stdio.h>
 #include "common.h"
 #include "optlist.h"
 
@@ -117,14 +118,42 @@ xyabsrange(struct natstr *np, struct range *src, struct range *dst)
     dst->height = src->height;
 }
 
-void
-inputxy(coord *xp, coord *yp, natid cn)
+/*
+ * Convert initial part of STR to normalized x-coordinate.
+ * Return -1 on error.  This works, as normalized coordinates are
+ * non-negative.
+ * Assign pointer to first character after the coordinate to *END,
+ * unless END is a null pointer.
+ */
+coord
+strtox(char *str, char **end)
 {
-    struct natstr *np;
+    long l;
 
-    np = getnatp(cn);
-    *xp = xabs(np, *xp);
-    *yp = yabs(np, *yp);
+    errno = 0;
+    l = strtol(str, end, 10);
+    if (*end == str || errno != 0)
+	return -1;
+    return XNORM(l);
+}
+
+/*
+ * Convert initial part of STR to normalized y-coordinate.
+ * Return -1 on error.  This works, as normalized coordinates are
+ * non-negative.
+ * Assign pointer to first character after the coordinate to *END,
+ * unless END is a null pointer.
+ */
+coord
+strtoy(char *str, char **end)
+{
+    long l;
+
+    errno = 0;
+    l = strtol(str, end, 10);
+    if (*end == str || errno != 0)
+	return -1;
+    return YNORM(l);
 }
 
 coord