switch to std.Io.net

[Wunka]

Related to #2338

This is not a real serious PR because for that I am not knowledgeable enough how the networking code works or what I forgot. (The stun servers need the resolveIP function but I can't get it to work for me with it... )
This was just a self learning experience for me and I didn't think I actually would get it to work but here we are.

But at least it works now and maybe someone can do better or use this as are starting point.

Current problems:

• When flying fast there are too many messages (I think) and some operation then blocks the client so long that the player stops until the the messages can be resolved.
• As mentioned above not all stun servers can be resolved.
• When using the port 0 to get a unused one from the OS I cant seem to get the now used one. (The address object doesn't change and I don't see something to get it, but maybe I am just blind.