Refactor ZOOM record render code and fix #2892.
Refactor ZOOM record render code and fix #2892.

Refactor code for ZOOM_record_get. The "xml" render for OPAC records
now renders the full OPAC. Previously only the MARCXML bibliographic part
was rendered (the bibliographic record). Pazpar2 relies on this
functionality and this should fix bug #2892.

nla/yaz,nla/yaz,dcrossleyau/yaz,dcrossleyau/yaz,nla/yaz,dcrossleyau/yaz,nla/yaz