Add constructors from date/time java.time types

[mlopes]

[mlopes]

A quick look at java.time shows that:

• ZoneDateTime
  • can be created from Instant
  • can be created from OffsetDateTime
  • can be created from ZonedDateTime
• DateTime can be created from LocalDateTime
• Date can be created from LocalDate
• ZoneTime can be created from OffsetTime
• Time can be created from LocalTime

[mlopes]

Probably a good idea to hold for #7 so that refinement of the date parts can be done in an easier way.

[mlopes]

Gave up on ZonedDateTime because the offset is from the zone, which makes it hard to do the right thing without the constructor being too smart, and make the behaviour unpredictable to the user.

I think it's preferable if the user converts to OffsetDateTime manually choosing the offset and then from there go to Wen's ZoneTIme