`default.nix` for building the project with `nix-build` using systems
`<nixpkgs>` and default compiler.
`shell.nix` to allow usage of `nix-shell` to enter development shell.
`default.nix` uses `withImplicitSnap = false` default.
To build with `implicitsnap` use
```
nix-build --arg withImplicitSnap true
```
`shell.nix` enables `withImplicitSnap` by default and can be overriden with
```
nix-shell --arg withImplicitSnap false
```