LUCENE-5160: check for -1 return conditions in file reads (cherry-picked https://svn.apache.org/r1512016 from branch_4x)
LUCENE-5161: set sane default readChunkSizes, make the setter work, and test the chunking (cherry-picked https://svn.apache.org/r1512729 from branch_4x)
LUCENE-5164: Fix default chunk sizes in FSDirectory to not be unnecessarily large (now 8192 bytes); also use chunking when writing to index files. FSDirectory#setReadChunkSize() is now deprecated and will be removed in Lucene 5.0 (cherry-picked https://svn.apache.org/r1512949 from branch_4x)