[Unit testing] Added additional checks comparing with `strftime`.
[Aux] Datetime generator now can parse week of the year placeholder (Sunday is the first day of the week).
[Aux] Datetime generator now can parse week of the year placeholder (Monday is the first day of the week).
[Code style] Tiny refactoring done.
[Aux] Datetime generator: Am/Pm support.
[Aux] Datetime generator: offset from UTC support.
[Aux] Datetime generator: timezone support.
[Aux] Datetime generator: `%%` sequence is now properly treated as single `%` character.