Lucene Index Filter for Values

Currently the Lucene filters for child path steps. Extend this option to include filters for specified values.

Example index query:
for $x in collection-from-index('data/books', '/bookstore/book/price', '>40')
return $x;

Example non-indexed:
for $x in collection('data/books')/bookstore/book/price
where $x>40
return $x;