LUCENE-6031: TokenStreamFromTermVector: move lazy init to incrementToken, hold payloads more efficiently; use PackedTokenAttributeImpl (save mem)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1647479 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6680: refactor DefaultSolrHighlighter.TermOffsetsTokenStream (from term vectors) to avoid buffering the token.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1647481 13f79535-47bb-0310-9956-ffa450edef68