add editorconfig to settings editors can be consistently unique (because we use tabs so people can set their own tab width)

Author: trusktr

.editorconfig

@@ -0,0 +1,15 @@
+# EditorConfig is awesome: http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+charset = utf-8
+indent_style = tab
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+indent_size = 2
+indent_style = space