Long-term this should make it easy to include all the GUI programs with
the desktop module and all the CLI programs with the shell module, as
well as the ability to easily disable sets of unneeded packages.
This was my attempt at migrating from diff-so-fancy to delta. Although
having an easy-to-hack-on rust code base was certainly appealing, there
are some minor inconveniences such as longer diffs by default.
The previous commit didn't actually work, and I shouldn't need to
change the variables often, so it's much simpler to not have them.
In the event that I do need to change something, rg and sd should get
the job done well.
