Version 2.2

• Rewrite of format and parse:
  • Many more types can be formatted and parsed with format and parse now.
    • durations, calendar types, tai_time, gps_time, ...
  • parse supports width parameter on many format flags.
  • to_stream and from_stream now return a reference to their streams.
  • Parsing whitespace very customizable with use of %n, %t and whitespace.
• Using the OS-supplied timezone database now an option on Linux and macOS.
• The downloaded timezone database install location can now be set at run time.
• Improved support for basic_string with custom allocator.
• duration I/O is merged into date.h.
• Make zoned_time and time_of_day "deduction guide ready" for C++17.
  • This eliminates the need for make_zoned and make_time in C++17.
• Many miscellaneous bug fixes.