howardhinnant-date

This is actually several separate C++11/C++14/C++17 libraries: - "date.h" is a header-only library which builds upon <chrono>. It adds some new duration types, and new time_point types. It also adds "field" types such as year_month_day which is a struct {year, month, day}. And it provides convenient means to convert between the "field" types and the time_point types. - "tz.h" / "tz.cpp" are a timezone library built on top of the "date.h" library. This timezone library is a complete parser of the IANA timezone database. It provides for an easy way to access all of the data in this database, using the types from "date.h" and <chrono>. The IANA database also includes data on leap seconds, and this library provides utilities to compute with that information as well. Slightly modified versions of "date.h" and "tz.h" were voted into the C++20 standard.