Attached 2 new classes:
A boolean query that only matches if a specified number of the contained clauses
match. An example use might be a query that returns a list of books where ANY 2
people from a list of people were co-authors, eg:
"Lucene In Action" would match ("Erik Hatcher" "Otis Gospodnetić" "Mark Harwood"
"Doug Cutting") with a minRequiredOverlap of 2 because Otis and Erik wrote that.
The book "Java Development with Ant" would not match because only 1 element in
the list (Erik) was selected.
A customised QueryParser that allows definition of
CoordConstrainedBooleanQueries. The solution (mis)uses fieldnames to pass
parameters to the custom query.