Bump JaCoCo version to snapshot (#466)
Re-enable Java 8 on Travis (#466)
Rewrite grouping cursor test in Java

Groovy and Java 8 have some problems with implementing iterators; this rewrites a test in Java to work around this problem (#466).
Bump to released JaCoCo 0.7
Fix JaCoCo version
Update Javadoc groupings
JavaDoc fixes for Java 8

Java 8's JavaDoc is stricter than Java 7's.  These fixes make the JavaDoc build.
Drop unused SQL statements