LUCENE-6825: merge trunk

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene6825@1709779 13f79535-47bb-0310-9956-ffa450edef68
tree: 2f50a3fbb921b9d876bcce72409e05fed34ca9ca
  1. dev-tools/
  2. lucene/
  3. solr/
  4. .gitignore
  5. .hgignore
  6. build.xml
  7. README.txt