Support NodaTime

[thargy]

Further to #36 (comment), is there any plan to support NodaTime fully, either via an additional shim package or just by including NodaTime in the core functionality?

For example, there's no easy way to fully implement

ZonedDateTime? GetNextOccurence(ZonedDateTime fromZoned, bool inclusive)

externally as you can't guarantee there's an equivalent System.TimeZoneInfo for any given NodaTime.DateTimeZone which is more feature rich. Whereas you can largely guarantee the opposite is true.