Subflakes should provide their wares as outputs, so wire up the pkgs
flake to reflect that.
Due to the unstable nature of flakes, updating the root flake doesn't
currently update the subflake lock file. Therefore, add additional
logic to flk update script in order to do this behind the scenes.
Nix is now pulled in from the "nix" registry flake in order for users
to take advantage of improvements to the UI since its last update in
nixpkgs.
- [x] refactor lib into separate files, similar to NixOS/nixpkgs/lib.
- [x] refactor ci to automatically generate derivations from flake outputs
- [x] remove cluttered indirection statements throughout the codebase
- [x] refactor hosts to allow for upcoming integration tests
- [x] improve ambiguity in the existing docs
- [x] add [BORS](https://bors.tech) support
- [x] add initial integration test
- [x] write tests documentation
- [x] test lib
- [x] improve version string generation, and do so automatically for pkgs/flake.nix sources
Clean up the codebase as best we can in preparation for #152 and add tests. From now on, all PRs will be merged with BORS.
