Hotfix!

This fixes the builder's ability to include offline sources and binaries into the resulting script.

The Polyglot Release

Nixie now officially supports macOS, which means the generated ./nix script can now be considered feature-complete.

There are still a few things (#4) I want to do before I'm ready to call it a bona fide release, but let that not deter early adopters of Nixie, for you can still run a quick nixie update afterwards.