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

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