DRILL-793: Fix output type's scale and precision for math functions.
Add alias names date_diff, date_sub alias to date subtraction functions
DRILL-976: Fix extract second to return only second portion of interval; exclude hours, minutes
DRILL-995: Removed inner form (which is not allowed). Fixed NPE and URLs.
Improve error messaging for OperatorStats assertion messages.
DRILL-1001: Expanded ProfileWrapper content and formatting.
DRILL-699: Allow case insensitive function names in queries.
DRILL-842: Aggregate function for correlation coefficient calculation
Enhancements to capture HashAggregate and HashJoin runtime metrics.
Improve OperatorStats to avoid leaking state.  Fix issue where HashJoinBatch throws NPE in stats tracking if we don't have HashTable.
DRILL-1009: Remove 'HBasePStoreProvider' from HBase storage module's drill-module.conf