LUCENE-5960: Use a more efficient bitset, not a Set<Integer>, to track visited states

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1625965 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5944: Bump version in trunk

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1625976 13f79535-47bb-0310-9956-ffa450edef68