Changed DayOfWeek::now() implementation
Removed DayOfWeek::fromDateTime() and FromDate()

These can be obtained from LocalDate::getDayOfWeek() and ZonedDateTime::getDayOfWeek(), respectively.
Refactored the DateTime\Timezone classes
Added nanosecond support to ReadableInstant comparison methods
Fixed a DateTime parser bug happening when nesting optional patterns

Refactored and added documentation.
Added nanosecond support to LocalTime