Remove unreferenced dbxrefs after ontology load
Update to version v757
Fix ontology load test
Add DESTROY() to OntologyIndex and fix test

In the test, don't open an index multiple times.
Clarify the Ubuntu CLucene installation
Fix documentation grammar
Do less work in PubMed load transactions
Don't run PubMed add in a transaction
Fix incorrect function name
Remove non-ASCII characters from the JSON dump
Update to version v758