Added tools config.

.editorconfig

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+# Configurations to normalize the IDE behavior.
+# http://editorconfig.org/
+
+root = true
+
+[*]
+indent_style = tab
+tab_width = 4
+charset = utf-8
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[package.json]
+indent_style = space
+tab_width = 2

.eslintrc.js

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+/**
+ * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/* eslint-env node */
+
+'use strict';
+
+module.exports = {
+	extends: 'ckeditor5'
+};

.gitattributes

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+*			text=auto
+
+*.htaccess	eol=lf
+*.cgi		eol=lf
+*.sh		eol=lf
+
+*.css		text
+*.htm		text
+*.html		text
+*.js		text
+*.json		text
+*.php		text
+*.txt		text
+*.md		text
+
+*.png		-text
+*.gif		-text
+*.jpg		-text

.stylelintrc

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+{
+	"extends": "stylelint-config-ckeditor5"
+}