Improve image serving
The serving of images could/should be improved by making use of the new picture
-tag. Using the picture-tag the browser can be served different formats and dimensions of an image. The browser then picks the best image for him. This makes it possible to for example serve modern WebP images to Chrome, Firefox and Edge while still supporting Safari and IE using JPGs.
More information about the picture-tag can be found here: https://developer.mozilla.org/de/docs/Web/HTML/Element/picture
A concept is required to implement the conversion to WebP and the creation/serving of the picture-tag.