DataCite Metadata v5.0 update list

[krzysztof]

Several backwards-compatibility solutions and implementation details that should be dropped with DataCite metadata 5.0:

1. Drop support for single geoLocationPolygon - schema users should generate geoLocationPolygons instead.
2. Drop support for type in the title, users should use titleType.
3. nameType should be a sub-property of creatorName/contributorName, instead of a direct sub-property of Creator/Contributor. This was kept this way to avoid changing the type of the creatorName/contributor name fiels from string to object between 4.0 -> 4.1 schema updates. In 5.0 nameType should be a subproperty of creatorName and contributorName, which by themselves should be objects like:

   "creatorName": {
     "type": "object",
     "properties": {"creatorName": {"type": "string"}, "nameType": {"enum":[..]}}
   }

4. DataCite requires four polygonPoint elements per geoLocationPolygon (and polygonPoint[0] == polygonPoint[-1]). So far JSON schema was requiring only 3 and was kept this way for geoLocationPolygon due to backwards compatibility, with a generation of a missing polygon when necessary (actually the auto-generation was not done until 4.1 upgrade, so it's not clear what the original intention was). The geoLocationPolygons also requires minimum 3 points. In new kernel, a decision needs to be made whether:
   1. 4 is the new minimum number of points, and the schema validation should fail if first point does not match the last point (or auto-generate)
   2. 3 remains to be the minimum number of points, and we continue to auto generate the last point.