Add base Makefile and nix environment

Makefile

@@ -0,0 +1,27 @@
+.PHONY: day1 day2 day3 day4 day5 day6 day7 day8 day9 day10 day11 day12 day13 day14 day15 day16 day17 day18 day19 day20 day21 day22 day23 day24 day25
+
+day1:
+day2:
+day3:
+day4:
+day5:
+day6:
+day7:
+day8:
+day9:
+day10:
+day11:
+day12:
+day13:
+day14:
+day15:
+day16:
+day17:
+day18:
+day19:
+day20:
+day21:
+day22:
+day23:
+day24:
+day25:

default.nix

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+with import <nixpkgs> {};
+stdenv.mkDerivation rec {
+  name = "env";
+  env = buildEnv { name = name; paths = buildInputs; };
+  buildInputs = [
+    php
+    gnumake
+  ];
+}