- Fixed UiSelect's selected item method

- Added a new DateTime (WIP from firefox still)

src/Ui.php

@@ -13,6 +13,7 @@ class Ui {
         $compiler->registerExtension(new Form\UiCheckbox());
         $compiler->registerExtension(new Form\UiColor());
         $compiler->registerExtension(new Form\UiDate());
+        $compiler->registerExtension(new Form\UiDatetime());
         $compiler->registerExtension(new Form\UiEmail());
         $compiler->registerExtension(new Form\UiFile());
         $compiler->registerExtension(new Form\UiHidden());