* Add .DS_Store to .gitignore
* Allow <= 999_999 as usec on DateTime (was < 999_999)
* Move [Tz]DateTime .format() to std::time::datetime and import only with libc
* Changed name to DateTimeFormat, prefer function over method. Move names to enum.
* Updated tests to the latest standard.
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Co-authored-by: Christoffer Lerno <christoffer@aegik.com>