LUCENE-4740: Don't track clones of MMapIndexInput if unmapping is disabled. This reduces GC overhead.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1441726 13f79535-47bb-0310-9956-ffa450edef68
Lucene-4733: Make CompressingTermVectorsFormat the new default term vectors format.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1441732 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-4733: More term vectors formats tests (TVReader.clone and TVWriter.merge).


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1441761 13f79535-47bb-0310-9956-ffa450edef68
Fix compilation under Java 6.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1441764 13f79535-47bb-0310-9956-ffa450edef68
Merged /lucene/dev/trunk:r1441568-1441570,1441572-1441769

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene4547@1441771 13f79535-47bb-0310-9956-ffa450edef68