Import dateutils-0.3.1 as wip/dateutils.

Dateutils are a bunch of tools that revolve around fiddling with
dates and times in the command line with a strong focus on use
cases that arise when dealing with large amounts of financial data.

Dateutils commands are prefixed with a `d` but otherwise resemble
known unix commands for reasons of intuition.  The only exception
being `strptime` which is analogous to the libc function of the
same name.