Dates with day == "00" get parsed regularly

[lucamug]

Iso8601.toTime "2000-01-00" returnsOk (Posix 946598400000)

Iso8601.toTime "2000-01-00" == Iso8601.toTime "1999-12-31" returns True

Ellie: https://ellie-app.com/hdDM5pmSv4Xa1 (edited)

[laurentpayot]

Confirmation here: https://stringy.guupa.com/MTk3MC0wMS0wMFQwMDowMDowMA/SXNvODYwMS50b1RpbWU

[jamesrweb]

@rtfeldman This can be closed when #30 is merged.