Add Open Graph and Twitter card. Prepare to allow changing the Title using shortcode

Using the new social icon and call it using the default social() function.

Create default TOC style with options to use the theme css

Even in posts collections page, create the TOC as long as its in full post mode.

Allow to add TOC using shortcode (<!--toc-->). TOC add button in text editor.

Reverting it for compatibility with old theme.

The `$p->video` should return the video link only, to get the video ID we can use get_video_id(); and call it from the theme.

We will change the date format in one go later.

system/htmly.php
- Loads language files from folder lang/
- Sets language settings for date and time format
system/includes/dispatch.php
- function i18n() returns translated strings

Glob() is expensive so cache the category files.

Make the footnote link absolute when on teaser

Added theme copyright for Twenty Fifteen & Twenty Sixteen.

The ported version of Twenty Fifteen and Twenty Sixteen include with the
package. Maintenance and bugs fixes.