Add rustfmt

.editorconfig

@@ -0,0 +1,10 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = tab
+indent_size = tab
+smart_tab = true

rustfmt.toml

@@ -0,0 +1 @@
+hard_tabs = true

shell.nix

@@ -1,5 +1,8 @@
 { pkgs ? import <nixpkgs> {} }:
   pkgs.mkShell {
-    packages = [ pkgs.cargo ];
+    packages = [
+      pkgs.cargo
+      pkgs.rustfmt
+   ];
 }