Note that the "2009" is quite important, a few things here are solved (though with the usual odd interface if you're not used to it).

> If that repository also has submodules, then your submodule’s submodules will have to be populated by following the steps below from within your project’s submodule directory (confusing yet?).

Now:

  git clone repo target
  cd target
  git submodule update --init --recursive

> Unfortunately, this is wrong. Git does not have a built in way to remove submodules.

It's a two stage process (the first cleans up .git/config, the second actually removes the code and submodule), but does exist now:

  git deinit lib/billboard
  git rm lib/billboard