Fix situation where repeated map vector was re-adding column name on second record batch.
DRILL-1695: Fix code generator comparisons
DRILL-1698: QueryWrapper creates a logger for FlattenRecordBatch class
DRILL-1434: In ParquetGroupScan compute the non-null value count of a column if stats are available for each chunk. Don't apply ConvertCountToDirectScan rule if stats are not available.
DRILL-1701: Choose the complex parquet reader when schema includes a simple map.
DRILL-1610: Don't apply partition pruning optimization if one of the disjuncts don't meet pruning criteria
Fix issue where 4 byte DrillBuf is sent even though there are no values when using varchar or repeated vector.