LUCENE-5619: add back-compat index+test for doc-values updates

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1594561 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5671: upgrade ICU to fix concurrency bug

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1594663 13f79535-47bb-0310-9956-ffa450edef68
SOLR-5973: Pluggable Ranking Collectors and Merge Strategies

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1594698 13f79535-47bb-0310-9956-ffa450edef68
log the message when required only

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1594801 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5667: add test case

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1594846 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5673: MMapDirectory: Work around a "bug" in the JDK that throws a confusing OutOfMemoryError wrapped inside IOException if the FileChannel  mapping failed because of lack of virtual address space. The IOException is rethrown with more useful information about the problem, omitting the incorrect OutOfMemoryError

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1595213 13f79535-47bb-0310-9956-ffa450edef68
Simplify for Java 7, which has support for new IOException(message, cause)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1595223 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5666: merge trunk

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5666@1595228 13f79535-47bb-0310-9956-ffa450edef68