demo site: standardise MARC

• Amends 773 to 909C4 field, except on journal collections.
• Amends 024 to 909CO field.
• Removes '<subfield code="2">DOI</subfield>' and adds 'doi' subfield to 909C4 field in record 96.
• Adds references (by refextract) to record 94 where they were missing.
• Amends affected tests in 'bibrecord_tests.py'.
• Amends 9094C to 909C4 field.
• Updates subfields values (c=pagination and v=volume).