POSIX command line argument parser.
- An option is a single alpha-numeric character, marked by a hyphen.
- More than one non-argument option may be grouped together.
- An option and its argument may or may not be separated by a space.
- Two hyphens stop the parsing of options.
- https://github.com/nlohmann/json for config file parsing
- add mutually exclusive arguments
- add argument groups
- add git-like sub-parsers