4.0.2

- We now force the number of documents of a virtual index to be equal
  to that specified by the resolver. Collections in which the last few
  documents were not referred would have generated virtual indices with
  fewer documents than the standard ones.

- Fixed a small bug in the equal method of Term.

- Fixed bug in the equals and hashCode methods of Select (before, only 
  Index was taken into account, and not the actual subquery).

- Fixed several small inconsistencies in the Scorer hierarchy.

- Added the SubsetDocumentSequence class to extract a subset of documents
  from a given sequence.

- Fixed the DEFAULT_TEMPLATE of QueryServlet.

- The default target for skipping structures is now 1%.

4.0.1

- Fixed the names of big lists by adding "Big" where it was necessary.
  This should cause no problem.

4.0

- First release of big MG4J.

- it.unimi.dsi.big.mg4j.search.DocumentIterator is now strictly lazy;
  in particular, it does not implement java.util.Iterator.
