LUCENE-5933: add FilterSpans

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1624329 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5936: Add backcompat checks to verify what is tested matches known versions

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1624330 13f79535-47bb-0310-9956-ffa450edef68