hadley/lubridate — pull request #290 by datalove (2014-12-27 15:16:10+00:00)
Title: Add isoyear function

Added `isoyear` function to match `isoweek`. i.e. `isoweek(ymd("2014-12-29"))` is `1`, but `year(ymd("2014-12-29"))` is `2014`, but we need `isoyear(ymd("2014-12-29"))` to be `2015`.