Feature request: Add ability for "Art Directed" images using the <picture> / <source> elements

[danny-englander]

Hi, it's great that srcset has been implemented in version 3 for responsive images. It would nice to allow for the <picture> element to be used for "Art directed" responsive images.

I think in this case, the <source> element would also be required so this might end up being a pretty big lift to implement. I started playing around with this in the code base for a while but did not get anywhere. Thank you.