DRILL-200, DRILL-196, DRILL-177, DRILL-201
Fix to address partition sender's incorrect reliance on allocator setValueCount fixes.  Remove old (no longer used) signature
DRILL-204: Basic SQL parallelization, add more hash functions and xor.
Backing out work on DRILL-204.  Wait until smarter optimizer because of issues with different types of aggregation functions and the need to break portions of the expression apart.
Fix regressions introduced by Parquet merge/ 63a90fe
DRILL-196, fix where setSafe was not correctly incrementing position of vector.
DRILL-165: Reorganize directories (moves only)
DRILL-186: Updated README.md