Network Package Interface

currently packages are send directly over the Socket, however it would be good if the ClientConnection and ServerConnection have multiple socket support (TCP and UDP socket) and the ClientPackage or ServerPackage has some kind of information like reliable, fast, e.t.c which is evaluated by the Connection so that the correct socket is choosen there. We could implement TCP, UDP, interprocess message https://github.com/veloren/game/issues/31