refactor!: finish parser migration

Finally! :)

This removes all code related to the old parser.

#65

lib/parser/classes/Grid.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const Parser = require('..');
+
+class Grid {
+  type = 'Grid';
+
+  constructor(data) {
+    this.items = Parser.parse(data.items);
+    this.is_collapsible = data.isCollapsible;
+    this.visible_row_count = data.visibleRowCount;
+    this.target_id = data.targetId;
+  }
+
+  // XXX: alias for consistency
+  get contents() {
+    return this.items;
+  }
+}
+
+module.exports = Grid;