Website now runs on Dart’s webdev

langue.phundrak.com now runs using the `webdev` tool from Dart.
Javascript code has been replaced with Dart code, and CSS code has
been replaced with SCSS code. To run the project, execute
`webdev serve` at the project’s root.

web/dart/cookie.dart

@@ -0,0 +1,11 @@
+@JS()
+library cookie;
+
+import 'package:js/js.dart';
+
+@JS()
+class Cookies {
+  // external factory Cookie();
+  external static String get(String name);
+  external static void set(String name, String value);
+}

web/dart/main.dart

@@ -0,0 +1,59 @@
+@JS()
+library main;
+
+import 'dart:html';
+
+import 'package:js/js.dart';
+import './cookie.dart';
+
+void main() {
+  reorganizeHtml();
+  createThemeSwitcher();
+  querySelector('.themeBtn').onClick.listen(themeSwitch);
+}
+
+void createThemeSwitcher() {
+  // set the correct CSS depending on the cookie, dark is enabled by default
+  var isDark = isThemeDark();
+  // Set the correct symbol in the theme switcher button
+  querySelector('body').append(DivElement()..className = 'themeBtn');
+  querySelector('.themeBtn')
+      .children
+      .add(Element.tag('i')..className = 'fas fa-' + (isDark ? 'sun' : 'moon'));
+}
+
+bool isThemeDark() {
+  if (Cookies.get('theme') == 'light') {
+    return false;
+  }
+  Cookies.set('theme', 'dark');
+  return true;
+}
+
+bool setTheme(bool dark) {
+  Cookies.set('theme', (dark ? 'dark' : 'light'));
+  return !dark;
+}
+
+void themeSwitch(MouseEvent event) {
+  print('Switch theme');
+  bool isDark = setTheme(isThemeDark());
+  querySelector('.fas').className = 'fas fa-' + (isDark ? 'sun' : 'moon');
+  querySelector('#theme').attributes['href'] =
+      '/css/' + (isDark ? 'dark' : 'light') + '.css';
+}
+
+void reorganizeHtml() {
+  // Add a <hr> element after the content div
+  querySelector('#content').appendHtml('<hr>');
+
+  // Move the postamble in the content div
+  querySelector('#content').append(querySelector('#postamble'));
+
+  for (var table in querySelectorAll('table')) {
+    var largetable = DivElement();
+    largetable.className = 'largetable';
+    table.before(largetable);
+    largetable.children.add(table);
+  }
+}