Add .editorconfig.

.editorconfig

@@ -0,0 +1,18 @@
+# EditorConfig configuration for my config -- See http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file, utf-8 charset
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+
+# tab_width defaults to set indent_size
+
+# Set indent to two spaces for Nix files.
+[*.nix]
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = true