Other: Add .editorconfigs

Add `.editorconfig`s, to help maintain a consistent coding style.
Also apply the new style to existing files.

.editorconfig

@@ -0,0 +1,15 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+charset = utf-8
+
+[*.{js,json}]
+indent_size = 4
+trim_trailing_whitespace = true
+
+[*.md]
+indent_size = 4
+trim_trailing_whitespace = false

docs/.editorconfig

@@ -0,0 +1,6 @@
+# Unset rules for `.js` files in this directory, since they might come from
+# external sources and therefore shouldn't be affected by this repos
+# `.editorconfig`.
+[*.js]
+indent_size = unset
+trim_trailing_whitespace = unset

src/extension.js

@@ -89,7 +89,7 @@ class Extension {
         const validLeftBoxOrder = this._createValidBoxOrder("left");
         const validCenterBoxOrder = this._createValidBoxOrder("center");
         const validRightBoxOrder = this._createValidBoxOrder("right");
-        
+
         // Go through the items (or rather their roles) of a box and order the
         // box accordingly.
         const orderBox = (boxOrder, box) => {