add itemKeys to MODS

[rettinghaus]

This PR adds a recordInfo to every Item on MODS export, containing the itemKey.
Proposed here: https://forums.zotero.org/discussion/76884

[annplaksin]

Thanks for adding the itemKeys to MODS.
This is very helpful!

[zuphilip]

Did you test this code? Two of the three lines are already in the code and the middle line should maybe moved to a better place. Moreover, you have to update the lastUpdate date at the beginning as well. Anyway, we should also discuss the PR in general.

[zuphilip]

Some considerations and things we should discuss:

1. Can you give an example MODS data produced by this modified translator?
2. Is it okay to save the URI in this field as well? (I haven't seen an example like that.)
3. What about the source attribute? According to the documentation If <recordIdentifier> is used, the DLF/Aquifer guidelines recommend the use of the source attribute if possible.
4. Should we consider this for importing as well? Most of our test cases have also a recordIdentifier field which could be imported as itemKey.

CC @adam3smith

[rettinghaus]

Example:

<?xml version="1.0" encoding="UTF-8"?>
<modsCollection xmlns="http://www.loc.gov/mods/v3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd">
  <mods>
    <titleInfo>
      <title>Das Orgelbüchlein des Mattseer Stiftsorganisten Johann Anton Graf aus dem Jahre 1738</title>
    </titleInfo>
    <titleInfo type="abbreviated">
      <title>Hintermaier 2002</title>
    </titleInfo>
    <typeOfResource>text</typeOfResource>
    <genre authority="local">journalArticle</genre>
    <name type="personal">
      <namePart type="family">Hintermaier</namePart>
      <namePart type="given">Ernst</namePart>
      <role>
        <roleTerm type="code" authority="marcrelator">aut</roleTerm>
      </role>
    </name>
    <recordInfo>
      <recordIdentifier>http://zotero.org/groups/2240469/items/2BQHJDF8</recordIdentifier>
    </recordInfo>
    <relatedItem type="host">
      <genre authority="marcgt">journal</genre>
      <part>
        <extent unit="pages">
          <start>84</start>
          <end>99</end>
        </extent>
      </part>
      <originInfo>
        <dateIssued>2002</dateIssued>
        <issuance>continuing</issuance>
      </originInfo>
      <titleInfo>
        <title>Bach - in Salzburg : Festschrift zum 25-jährigen Bestehen der Salzburger Bachgesellschaft ; eine Dokumentation des Symposions zum Bach-Jahr 2000 in Salzburg nach einer Idee von Albert F. Hartinger und Siegfried Mauser mit ergänzenden Beiträgen</title>
      </titleInfo>
    </relatedItem>
  </mods>
  <mods>
    <titleInfo>
      <title>Das Plauener Orgelbuch von 1708</title>
    </titleInfo>
    <typeOfResource>text</typeOfResource>
    <genre authority="local">journalArticle</genre>
    <name type="personal">
      <namePart type="family">Seiffert</namePart>
      <namePart type="given">Max</namePart>
      <role>
        <roleTerm type="code" authority="marcrelator">aut</roleTerm>
      </role>
    </name>
    <identifier type="doi">10.2307/929596</identifier>
    <location>
      <url usage="primary display" dateLastAccessed="2019-03-01 11:12:19">https://www.jstor.org/stable/929596</url>
    </location>
    <recordInfo>
      <recordIdentifier>http://zotero.org/groups/2240469/items/CJ8I7FRF</recordIdentifier>
      <recordContentSource>JSTOR</recordContentSource>
    </recordInfo>
    <relatedItem type="host">
      <genre authority="marcgt">journal</genre>
      <part>
        <detail type="volume">
          <number>2</number>
        </detail>
        <detail type="issue">
          <number>3</number>
        </detail>
        <extent unit="pages">
          <start>371</start>
          <end>393</end>
        </extent>
      </part>
      <originInfo>
        <dateIssued>1920</dateIssued>
        <issuance>continuing</issuance>
      </originInfo>
      <identifier type="issn">0003-9292</identifier>
      <titleInfo>
        <title>Archiv für Musikwissenschaft</title>
      </titleInfo>
    </relatedItem>
  </mods>
</modsCollection>

[rettinghaus]

Thanks for the comments.
Originally I thought to put the URI into the <identifier>, but Zotero already puts in there the DOI/URI of the item. I'm not sure it's ok to mix the URI of the record with the URI of the item, so I put it in the <recordIdentifier>.

Others put the the record ID into recordIdenifier and the URI (which contains the ID) into <identifer>, e.g.:
http://kalliope.staatsbibliothek-berlin.de/en/standards/sru.html
http://kalliope-verbund.info/sru?version=1.2&operation=searchRetrieve&query=ead.id=DE-611-HS-1839379&recordSchema=mods

Any better idea where to store it?