upgrade-1.4.0d3-1.4.0d4.sql

Handle correctly the indexing of moderated messages in fulltext search:

so far the fulltext search would also include unapproved messages and threads. With this reform we address this by:
- making sure unapproved threads are deleted from the index
- making sure new threads are added to the index only when the are approved
- making sure we unindex or reindex a thread whenever the approval state changes
- not fetching unapproved messages in the datasource callback, hence excluding them from the index

Note that Oracle has not been targeted by the reform. However, the situation improves for Oracle as well, because we won't render unmoderated messages in the datasource callback anymore.