Add contrib/isn module for ISBN/ISSN/EAN13/etc product numbers, and

remove the old isbn_issn module which is about to be obsoleted by EAN13.
contrib/isn is by Germán Méndez Bravo.  Our thanks to Garrett A. Wollman
for having written the original isbn_issn module.

contrib/isn/UPC.h

@@ -0,0 +1,28 @@
+/* 
+ * ISSN.h
+ *	  PostgreSQL type definitions for ISNs (ISBN, ISMN, ISSN, EAN13, UPC)
+ *
+ * No information available for UPC prefixes
+ * 
+ *
+ * IDENTIFICATION
+ *	  $PostgreSQL: pgsql/contrib/isn/UPC.h,v 1.1 2006/09/09 04:07:52 tgl Exp $
+ *
+ */
+
+/* where the digit set begins, and how many of them are in the table */
+const unsigned UPC_index[10][2] = {
+	{0,		0},
+	{0,		0},
+	{0,		0},
+	{0,		0},
+	{0,		0},
+	{0,		0},
+	{0,		0},
+	{0,		0},
+	{0,		0},
+	{0,		0},
+};
+const char *UPC_range[][2] = {
+	{NULL, NULL}
+};