Annotations may disappear if records are reloaded

Field annotations may disappear from the VRE interface if records are reloaded from the Explorer in two cases:

* Annotations to fields that are missing from the original records disappear if the original record later includes these fields
* Annotations to fields that are present in the original record disappear if the values of the field change in the source database

The annotations will remain present in the triplestore and are also loaded to the frontend, but the frontend won't render them.