Enhance Searcher interface

Current Searcher interface is too limited for many purposes:

Hits search(Query query, int numHits, String dedupField, String sortField,
boolean reverse) throws IOException;

It would be nice that we had an interface that allowed adding different features without changing the interface. I am proposing that we deprecate the current search method and introduce something like:

Hits search(Query query, Metadata context) throws IOException;

Also at the same time we should enhance the QueryFilter interface to look something like:

BooleanQuery filter(Query input, BooleanQuery translation, Metadata context)
throws QueryException;

I would like to hear your comments before proceeding with a patch.