[packaging-on-the-web] Icon container as use case (#22)

Half-baked idea... 

As screen densities increase, and web apps become "installable", it's likely to become more common that developers include high resolution icons pertaining to their web applications into either a container or directly into HTML using multiple `<link rel=icon>`s.
 
One can use a .ico file to contain icons, but the max. size of an icon can only be 256x256. Apple's .icns file format supports larger icons, but it's a proprietary format and not widely supported by browsers. 

A generic packaging format could potentially help address the shortcomings with .ico. Particularly if the central directory included some metadata about each file (e.g., width, height, and maybe target density).  

---
Reply to this email directly or view it on GitHub:
https://github.com/w3ctag/packaging-on-the-web/issues/22