Bypass DuckDuckGo icon lib

[AkarinLiu]

My Server Can`t Access DuckDuckGo icon lib, I hopely next update support get icon from source website.

[clarkwinkelmann]

This is not an easy fix.

Assuming you know the path to the favicon on the destination website, it would not be responsible to load it directly from the remote server, as you could involuntarily send a denial of service attack onto the destination website if your forum is more popular than the destination.

Another problem to a "simple" solution is that the path to the favicon cannot be guessed, so server-side logic is required to fetch the homepage, find the favicon URL, and refresh this information as time goes on.

Part of self-hosting the solution would require caching the icons. There are filesystem concerns with this (how big are the icons, how many will be stored), and along with fetching the homepage, this will leak the server IP to external websites, which might be undesirable.

The easiest fix would simply be to offer a choice for an alternative external icon proxy. I believe Google has one as well.

If there exists a self-hosted icon proxy script, there could be a setting in our extension to provide a custom URL to the self-hosted script. We would need to know what the URL syntax look like to automatically inject the destination website name in it.

Fixing #31 would likely be a pre-requirement to implement this, because any existing proxy URL currently gets permanently memorized, and a toggle for other than DuckDuckGo would have no impact on all links already created.