argparse

Feature-rich command line parser for Lua inspired by argparse for Python.

WIP.

TODO L1

• Document NYI declarative interface. Choices, converters.
• Write tests related to NYI declarative interface.
• Implement NYI declarative interface.

TODO L2

• Document parsing.
• Write tests related to parsing.
• Refactor/rewrite parsing stuff.
• Current Parser class should be just a container for information used in parsingm such as options, commands, etc. The relation between Parser and ParserState should be reversed; ParserState should be the actual parser; it should process args and query Parser when needed.
• - shouldn't be the only character for options/flags. Infer all of them from first characters of option aliases.
• Suggestions for command typos. E.g. $ luarocks isntall -> Did you mean 'install'?