refactor!: finish parser migration

Finally! :)

This removes all code related to the old parser.

#65

lib/parser/classes/TextHeader.js

@@ -0,0 +1,14 @@
+'use strict';
+
+const Text = require('./Text');
+
+class TextHeader {
+  type = 'TextHeader';
+
+  constructor(data) {
+    this.title = new Text(data.title);
+    this.style = data.style;
+  }
+}
+
+module.exports = TextHeader;