Changelog for grid

7.8.15 Simplified nix config again.

7.8.14 Simplified nix config.

7.8.13 Updated copyright year.

7.8.12 Revamped to work with Nix + cabal-install.

7.8.11 Revamped to work with Nix + Stack.

7.8.10 Revamped to work with Stack v1.7.1.

Unreleased changes