for clarity's sake, expose which function uses final and prev, so that
people can have a clearer understanding how they relate to each other
in terms of dependencies.
also a simple `{ lib = final; }` probably does not warrant a complete
callLibs obscurization.
- [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.