TODO

[thetredev]

• Add Windows support
• Add support for positional arguments which are neither flags nor options
• Provide richer samples
• Add support/readme for custom types

After all that...

• Make struct types::CommandLineArgument_t a class which one can use directly to call get<T>([<default>]) on it to get its typed command line value
  This will require creating an parser::ArgumentParser on the heap using something like std::unique_ptr and a public static creator() method.

[thetredev]

Windows support isn't working yet. See #3