POSIX socket API wrapper written in Swift.

Here’s a very incomplete list of things that could be added or changed:

• Implement support for other protocols than TCP. The low-level Socket struct probably doesn’t need any changes for that, but the higher-level SocketType sub-protocols don’t expose initializers for that.
• getaddrinfo() returns a linked list of results and only the very first one is used for connect()/accept(). That list should probably be traversed until those calls actually succeed.

Updated from SocketWrapper