Provides printing and parsing support for instants and durations. This package contains simple and advanced classes for formatting.

Formatters are defined by interfaces, and instances are obtained from factory classes. Most datetime formatters can be obtained from `DateTimeFormat` and `ISODateTimeFormat`. More advanced formatters can be built by using `DateTimeFormatterBuilder`.

Similarly there are also classes for parsing and printing periods. Most period formatters can be obtained from the factory classes `PeriodFormat` and `ISOPeriodFormat`. More advanced formatters can be built by using `PeriodFormatterBuilder`.