Updated ``Zepto\FileLoader\MarkdownLoader`` to not return empty key-values in ``meta`` and updated template check in ``Zepto\Zepto``
Added blocks to and updated base.twig
Cleaned up tests for ``Zepto\FileLoader\MarkdownLoader``
Cleaned up config.php, added ‘.’ to ``content_ext``
Fixed file extension issue in ``Zepto\FileLoader``
Added ``Zepto\Zepto::create_nav_links()`` to create navigation links