Better civil footnote support

In infinite scroll situation, the sliding instead of jumping mechanism
will still work now
Fixing editor styling

- Loading roboto on tinyMCE
- Adding #tinymce class to body selector of editor
Using protocol relative url for fonts

As suggested on the trac: https://themes.trac.wordpress.org/ticket/20086
Adding Phillip Arthur's Subtitles Plugin support

It looks good with subtitle now
Adding subtitles support on readme