Static import DateTimeZoneIndex.unpackChronology into DateTimeFunctions
Simplify date time field calculations

Add quarter of year date time file for consistency
Add utility method to get a DateTimeField for a chronology
Add date_add and date_diff for time and date types
Add date_trunc function
Remove century date time field
Remove unnecessary methods from BlockBuilder
Clean up new Type and Block SPIs

Add JavaDocs
Rename methods and parameter names
Cleanup IDE warnings

Add missing @Override annotations
Replace uses of StringBuffer with StringBuilder
Make utility classes final
Rename NullType to UnknownType and move to presto-main
Require Type implementations to have a getInstance method