This removes need for TCP network connection in single-player games.
Instead, game will now create internal pseudo-connection that performs
client<->server communication by posting sent messages to client/server
asio::io_service'a.
This should fix gameplay aborting on switching to another app on iOS (and
apparently, on Android in some cases)
At the moment, vcmilobby *requires* async writes in order to handle
multiple connections with different speeds and at optimal performance,
without hanging if one player is too slow and can't eat all data server
sent to him at once.
However server (and potentially - client) can not handle this mode and
may shutdown either socket or entire asio service too early, before all
writes are performed, leading to weird freeze on ending scenario where
client would not receive notifications about end of game.
