DRILL-713: Fix resizing of the hash table.
Fix alignment in Hash Join code
DRILL-757: Output mutator interface changes
- Output mutator manages schema changes instead of record readers
- Removed usages of deprecated interface
DRILL-769: Remove swapping using decimal holders.
DRILL-770: Fix decimal math functions with constants
DRILL-771: Remove explicit cast to varchar for concat() function; implicit cast will be used.
DRILL-588: Ignore leading zeroes while determining if digits will fit in a given precision
DRILL-776: Support SelectionVector SV2 and SV4 in Partition Sender.
DRILL-768: Support 2 phase COUNT() aggregates.

Create a new SUM aggregate function whose return type is non-nullable to match the return type of COUNT.
enable multi-phase aggregate by default
DRILL-764: Add support for 'convert_to()' and 'convert_from()' functions from SQL
DRILL-671: Select against hbase table with filter against row_key fails
DRILL-783: Convert function support in HBase filter push down.

+ Enable HBase test suit (failures fixed by DRILL-761).
DRILL-781: Use MapVector as the top level vector for HBase Column Families