Add a .editorconfig

.editorconfig

@@ -0,0 +1,19 @@
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+# Indent JS with four spaces
+[*.js]
+indent_style = space
+indent_size = 4
+
+# Indent HTML with two spaces
+[*.html]
+indent_style = space
+indent_size = 2