Also add "gui-pkg-manager" packages, including a "Racket Package Manager"
GUI application (that needs a better icon).
The package that supplies "Racket Package Manager" is not in the main
distribution, since DrRacket already includes the GUI package manager.
The "racket" directory contains a pared-back version of the
repository, roughly.
The "pkgs" directory everything else in the repository, but
organized into packages.
