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

Log Message:
-----------
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 Germ�n M�ndez Bravo.  Our thanks to Garrett A. Wollman
for having written the original isbn_issn module.

Modified Files:
--------------
    pgsql/contrib:
        Makefile (r1.69 -> r1.70)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/Makefile.diff?r1=1.69&r2=1.70)
        README (r1.90 -> r1.91)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/README.diff?r1=1.90&r2=1.91)

Added Files:
-----------
    pgsql/contrib/isn:
        EAN13.h (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/EAN13.h?rev=1.1&content-type=text/x-cvsweb-markup)
        ISBN.h (r1.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/ISBN.h?rev=1.1&content-type=text/x-cvsweb-markup)
        ISMN.h (r1.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/ISMN.h?rev=1.1&content-type=text/x-cvsweb-markup)
        ISSN.h (r1.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/ISSN.h?rev=1.1&content-type=text/x-cvsweb-markup)
        Makefile (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/Makefile?rev=1.1&content-type=text/x-cvsweb-markup)
        README.isn (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/README.isn?rev=1.1&content-type=text/x-cvsweb-markup)
        UPC.h (r1.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/UPC.h?rev=1.1&content-type=text/x-cvsweb-markup)
        isn.c (r1.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/isn.c?rev=1.1&content-type=text/x-cvsweb-markup)
        isn.h (r1.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/isn.h?rev=1.1&content-type=text/x-cvsweb-markup)
        isn.sql.in (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/isn.sql.in?rev=1.1&content-type=text/x-cvsweb-markup)
        uninstall_isn.sql (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/uninstall_isn.sql?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    pgsql/contrib/isbn_issn:
        Makefile
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isbn_issn/Makefile)
        README.isbn_issn
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isbn_issn/README.isbn_issn)
        isbn_issn.c
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isbn_issn/isbn_issn.c)
        isbn_issn.sql.in
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isbn_issn/isbn_issn.sql.in)
        uninstall_isbn_issn.sql
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isbn_issn/uninstall_isbn_issn.sql)