D-Net

avoid the index records preparation procedure to fail in case of missing context ids

implemented use of opt in/out rules for entity fields (#2557)

Keep working with the entity config for customizing XML serialization

#2557: only serialise fields as defined by the Index Config

Enables the fix for #2557: new two fields for the index configuration to include/exclude fields to be serialised in the final XML records.

tests for affiliation relationships

test for #2544: Datasets without instance URL in beta

datasources with piwik ids

updated config for rel expansion to include result's collectedfrom