Material icons are fetched at runtime

The Channel Manager uses Material Design icons. These are fetched at runtime via an external link to googleapis.com:

<link href="//fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet">

As a result, the CMS always needs access to this external resource. That can be annoying when running it behind a firewall, or when developing the CMS offline.

The CMS should not need any external resources to function. All Material icons (or just all used ones) should be included in the distributed artifacts, just like all other icons in the CMS.