Add support for Facebook video posts, and for feeds

[wpdavis]

Adds support for video posts matching https?://(www)?.facebook.com/[^/]+/videos/[\d]+

Also, moves the Facebook script call inline, else the embed fails in instances where wp_footer is not called (i.e. in feeds)

[wpdavis]

I know it's dirty to put JS inline. Any ideas on a better way to do this? Maybe something like

if( is_feed() ) { \\do things inline } elseif( ! has_action( 'wp_footer' ) ) { \\enqueue }

[danielbachhuber]

Also, moves the Facebook script call inline, else the embed fails in instances where wp_footer is not called (i.e. in feeds)

Why would you want to add the Facebook script to a feed?

[wpdavis]

For us it's specifically because our apps our powered through our feeds. But in general, if there's a JSON response with the content of the post, for example, generally I would think it should include everything needed to render the content. In this case as well there isn't a plain-HTML fallback. Definitely depends on the application, though.

[davisshaver]

Regarding feeds – we've previously discussed an abstraction that lets us callback a separate feed function to handle this use case. #30 I'm hesitant to place the script calls inline a feed – standards also advise against it

Can we do a new PR with the Facebook videos regex tweak and discuss the context switching here? #38