Converts a time entity to a map of property key -> value as defined by the
passed in `value-fn`. By default the actual value of the unit/field is
produced.

  (as-map (duration))
  => {:nanos 0, :seconds 0}

  (as-map (local-date 2015 1 1))
  => {:year 2015, :month-of-year 1, :day-of-month 1, ...}

Converts an amount from one unit to another. Returns a map of:
  * `:whole` - the whole part of the conversion in the `to` unit
  * `:remainder` - the remainder in the `from` unit

Arguments may be keywords or instances of `TemporalUnit`.

Converts between precise units - nanos up to weeks, treating days as exact
multiples of 24 hours. Also converts between imprecise units - months up to
millenia. See `ChronoUnit` and `IsoFields` for all of the supported units.
Does not convert between precise and imprecise units.

Throws `ArithmeticException` if long overflow occurs during computation.

  (convert-amount 10000 :seconds :hours)
  => {:remainder 2800 :whole 2}

Converts a date entity to a `java.util.Date`.

Converts a date entity to a `long` representing the number of milliseconds
from epoch.

Converts a date entity to a `java.sql.Date`.

Converts a date entity to a `java.sql.Timestamp`.