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
Avoid undefined value from join in PubMed loading
Add DOI number and OA logo to Canto paper link
Work around bug in Cache module
Die if no term name is passed to get_cvterm()
Update to version v759
Mention GMOD on the front page
Update to version v760
Add a better front page title in HEAD section
Update to version v761
Link directly to the GMOD Canto wiki page
Fix the destination of evidence page button "back"
Update to version v762