argparse v2.2.1

• We now support the following ArgumentParser() methods:

  • format_help()
  • format_usage()
  • parse_intermixed_args() (#45)
  • parse_known_intermixed_args() (#45)
  • set_defaults() (#43). Suggestion of @oliverbothe.

• When an error is thrown by ArgumentParser()$parse_args() and interactive() is FALSE
  and getOption("error") is NULL then
  we now use a quieter default error handler that doesn't output a trailing "Execution halted".

• add_argument() now allows "numeric" as an alias for "double" for the type argument (#42).
  Suggestion of @dariober.

• ArgumentParser() now handles description arguments with newlines in them (#44).
  Thanks Arthur Gilly (@agilly) for bug report.