feat(nix): nix and back again

I tried Nix, but it had too many downsides so I removed it.

1. Didn't like that all files are immutable and simple config changes
need a complete rebuild.
2. Setting up a new Mac didn't work as smoothly as promised. Not worth
the effort.
3. It sucked a lot to always have to type in the password twice on each
darwin-rebuild
4. It solves problems I never had.

.editorconfig

@@ -0,0 +1,18 @@
+# http://editorconfig.org
+
+# Root file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = tab
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{md,markdown,pandoc}]
+trim_trailing_whitespace = false
+
+[Makefile]
+indent_style = tab