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/ISMN.h

@@ -0,0 +1,52 @@
+/* 
+ * ISMN.h
+ *	  PostgreSQL type definitions for ISNs (ISBN, ISMN, ISSN, EAN13, UPC)
+ *
+ * Information recompiled by Kronuz on November 12, 2004
+ * http://www.ismn-international.org
+ *
+ * IDENTIFICATION
+ *	  $PostgreSQL: pgsql/contrib/isn/ISMN.h,v 1.1 2006/09/09 04:07:52 tgl Exp $
+ *
+ * M-3452-4680-5 <=> (0)-3452-4680-5 <=> 0345246805 <=> 9790345246805 <=> 979-0-3452-4680-5
+ *
+ *             (M counts as 3)
+ * ISMN         M   3   4    5   2   4   6    8   0
+ * Weight       3   1   3    1   3   1   3    1   3
+ * Product      9 + 3 + 12 + 5 + 6 + 4 + 18 + 8 + 0 = 65
+ *              65 / 10 = 6 remainder 5
+ * Check digit  10 - 5 = 5 
+ * => M-3452-4680-5
+ *
+ * ISMN         9   7    9   0   3   4    5   2   4   6    8   0
+ * Weight       1   3    1   3   1   3    1   3   1   3    1   3
+ * Product      9 + 21 + 9 + 0 + 3 + 12 + 5 + 6 + 4 + 18 + 8 + 0 = 95
+ *              95 / 10 = 9 remainder 5
+ * Check digit  10 - 5 = 5 
+ * => 979-0-3452-4680-5
+ *
+ * Since mod10(9*1 + 7*3 + 9*1 + 0*3) = mod10(M*3) = mod10(3*3) = 9; the check digit remains the same.
+ *
+ */
+
+/* where the digit set begins, and how many of them are in the table */
+const unsigned ISMN_index[10][2] = {
+	{0,		5},
+	{5,		0},
+	{5,		0},
+	{5,		0},
+	{5,		0},
+	{5,		0},
+	{5,		0},
+	{5,		0},
+	{5,		0},
+	{5,		0},
+};
+const char *ISMN_range[][2] = {
+	{"0-000", "0-099"},
+	{"0-1000", "0-3999"},
+	{"0-40000", "0-69999"},
+	{"0-700000", "0-899999"},
+	{"0-9000000", "0-9999999"},
+	{NULL, NULL}
+};