srcset needed on featured image

[tjhdesign]

Hi - amazing theme! One thing that would be a big help/fix is to have a proper srcset on the featured image on posts.

As it stands, Hueman loads the highest resolution possible, up to 1,320px, no matter what. I realize this was a fix for a previous issue (#866), but now page speed on mobile devices is needlessly slowed with an unnecessary high-res download.

So, instead of how it currently handles the image...

<div class="image-container">
  <img src="image.jpg" alt="Image" width="1320" height="500">
</div>

... could we have something like this?

<div class="image-container">
  <img alt="Image" width="1320" height="500" srcset="image-1320w.jpg 1320w, image-1024w.jpg 1024w" src="image-1320w.jpg">
</div>

Thanks!