Merge data with same id on solr upload
Current problem:
If an entry with an ID exists in the index, per default the indexer does not reindex the entry, no matter if the new entry has more content.
It is possible to force reindexing.
A merging strategy would be a nice thing. One the other hand one could argue that this should be cared for on the uplifting part and then all entries have ideally the same depth.
Something like this might be needed anyway for other features for the front end, like a list of publications of a certain person, etc.