Bug 25964: Prevent data loss when editing items from a MARC record

Bug 25964: Prevent data loss when editing items from a MARC record

Coming from:
  Bug 23463: Use new method Koha::Object->set_or_blank

We have DB fields that are not mapped with MARC fields, for instance paidfor. They are not handled correctly.

In ModItemFromMarc, we get a MARC record in parameter and update the item in DB. But we are loosing the fields that are not in the MARC record

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 189851fb9bbc831bb2875c2c440877c2562583d0)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>