DRILL-6094: Decimal data type enhancements
Add ExprVisitors for VARDECIMAL
Modify writers/readers to support VARDECIMAL
- Added usage of VarDecimal for parquet, hive, maprdb, jdbc;
- Added options to store decimals as int32 and int64 or fixed_len_byte_array or binary;
Add UDFs for VARDECIMAL data type
- modify type inference rules
- remove UDFs for obsolete DECIMAL types
Enable DECIMAL data type by default
Add unit tests for DECIMAL data type
Fix mapping for NLJ when literal with non-primitive type is used in join conditions
Refresh protobuf C++ source files
Changes in C++ files
Add support for decimal logical type in Avro.
Add support for date, time and timestamp logical types.
Update Avro version to 1.8.2.
