Group and tile contiguous images

[kdeldycke]

The idea is to have a way to detect images featured in a post that are not separated by written content, and then group them, and eventually assemble them into tiles.

TL;DR: we need an advanced lightbox gallery plugin.

Inspiration:

• https://github.com/sachinchoolur/lightgallery.js/
• https://github.com/crowdfavorite-mirrors/wp-jetpack/tree/master/modules/tiled-gallery
• https://github.com/jakobholmelund/fitpicsjs