bug 4169: fix item batch modification for MARC21

bug 4169: fix item batch modification for MARC21

The MARC21 framework uses $0 for the item withdrawn status.  Because
of how the tool had marked the barcode and stocknumber as being
uneditable, this resulted in an off-by-one error, causing the wrong
item fields to be updated.

Fixed by simply not including the uneditable fields in list
of item fields that can be edited - if you can't change the barcode,
there's no point in displaying it in the list of fields.

Also fixed how the bib title/author/ISBN got displayed so that the
withdrawn column gets displayed after an item update.

Signed-off-by: Galen Charlton <gmcharlt@gmail.com>
Signed-off-by: Liz Rea <lrea@nekls.org>