- A Display has Screens
- A Screen has Monitors & Windows
- The root Screen is accessed by traversing to the head of the list of
  screens using an interator.
- The root screen's root window is used as the parameter for
  'get_screen_resources'.
- The screen_resources object is contains 'screen_resources_crtcs',
  which you again get via an iterator. These are cookies.

CXX Opts looks like a really useful version of GetOpts that will do what you want:
https://github.com/jarro2783/cxxopts


# Git

- `git submodule add <url>` is how you add a submodule to your project.  It
  creates a new folder for the submodule and it creates an entry in the
  `$(git-root)/.gitmodule` file that explains where the submodule should go and
  how to reference it.