26w29a: Steam p2p connection

As I was having some trouble to reproduce the connectivity issue, I finally bit the bullet and decided to implement steam p2p.

You will be able to create a multiplayer lobby only open to your friends for now. I will add more options and features, tell me what is the most urgent!

I did a pass a fixed quite a few issues but I expect plenty of issues still.

There are things still missing, like npc/crew walking in stations.

For now do not expect to play a serious survival game, it is better to simply build with friends!

Thanks for playing!