LUCENE-5812: NRTCachingDirectory now implements Accountable

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1609465 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5714: BBoxStrategy should convert shapes to bounding box on indexing (but not search)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1609469 13f79535-47bb-0310-9956-ffa450edef68