TODO

 - Upgrade Lucene version to 2.9.3 and fix tests (if there are failures).

 - Remove code using deprecated Lucene APIs and upgrade to Lucene 3.0.x.

 - Investigate concurrency issues related to QueryParser not being thread
   safe and consider constructing a new QueryParser per request.

 - Decide how many results to return when the user does not specify it,
   1000? More?

 - Should we use the index to suppress duplicates instead of in-memory
   data structures?

 - How do we implement removals/unindex?
    - We could use the Model to decide when there are no more triples with
      a specified literal and therefore it's ok to remove it from Lucene.

 - See how the new NRT capabilities of Lucene can be used from LARQ.

 - Think about how ARQ could initialise LARQ checking in the classpath.
   (LARQ depends on ARQ, therefore ARQ should not depend on LARQ to avoid
   a cycle in our dependencies).

 - Publish artifacts to the http://www.openjena.org/repo-dev/ and /repo/
   repositories, can we use maven-release-plugin there?

 - Review package names (currently c.h.h.j.sparql.larq and c.h.h.j.query.larq).
   Should we move to c.h.h.j.larq.*?

 - Check if https://github.com/castagna/LARQ is still necessary, if not
   remove it and/or point at SVN on SourceForge.

 - Add an assembly.xml to distribute LARQ, or we should avoid this and
   just publish the jar and distribute it with ARQ.