Bug 8680 Z39.50 ISBN Search is problematic and there is a missing ISSN field.

Bug 8680 Z39.50 ISBN Search is problematic and there is a missing ISSN field.

The changes here are duplicate fixes.
The cataloguing directory had the same bugs as the acqui directory.
The bugs in the cataloguing files of the same name were fixed in Bug 8550.
The bugs in the acqui files had not been fixed.
This will fix Bug 8680 which is in the Acquisitions Module.

Changes to the z3950_search.pl file:
Rather than treating ISBN and ISSN as the same, this patch breaks
them out into separate parts of the query, as well as changing
the truncation attribute to enable right truncation (the correct
behavior for the ISBN field in MARC21, and valid behavior in
UNIMARC).

Changes to the z3950_search.tt file:
Sometime in 2009 or so, the ISSN field was removed from the Z39.50 search
page, and the ISBN field replaced with a combined ISBN/ISSN field. Since
this breaks ISBN search for most Z39.50 targets (due to the
differing treatment of ISBN vs. ISSN), this is a bug not a feature.

Signed-off-by: Marc Veron <veron@veron.ch>
Works as expected.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>