LUCENE-5864: Split BytesRef into BytesRef and BytesRefBuilder.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1617695 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6062: Fix undesirable edismax query parser effect (introduced in SOLR-2058) in how phrase queries generated from pf, pf2, and pf3 are merged into the main query. (merged from trunk r1617719)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1617721 13f79535-47bb-0310-9956-ffa450edef68