Added map_keys and map_values functions
Fix Exception when using subscript operator in aggregation query
Fix RcFilePageSource handling of offset and length
Cleanup formatting and exception types
Handle nested maps correctly in map_keys
Add utility methods for reflection
Update to Airbase 28 with Guava 18.0
Use release version of Airbase 28
Improve Driver performance

Measure CPU time only once per quanta
Acquire lock only once per quanta
Update to new ColumnProjectionUtils.appendReadColumns api

Remove usage of ColumnProjectionUtils.setReadColumns
Remove setting of "column" property
Rename misnamed variable in ORC stream readers
Add support for literal parameters in type signatures
Support parametric types with literal parameters
Refactor AbstractType constructor to take TypeSignature
Change ModelType to extend AbstractVariableWidthType
Allow types to customize the name displayed in DESCRIBE
Remove partial support for Hive UNION type
Implement ROW type
Change Hive structs to be ROWs instead of VARCHARs
Add support for variadic type parameters