LUCENE-5274: FastVectorHighlighter now supports highlighting against several indexed fields


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1534281 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5294: simmer down, validate-maven-dependencies

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1534430 13f79535-47bb-0310-9956-ffa450edef68
refactor Collector interface for lock-free parallelizability
parallelize TopScoreDocCollector
parallelize FacetsCollector
parallelize TopFieldCollector