Add IOCP.Mswsock

This is basically a clone of IOCP.Winsock.Load, but without the
WSAStartup call, which is now left to the network package.
I'm switching to the network package, and plan to remove my
versions of things like SockAddr.
Update testsuite

 * Remove initWinsock call.  My network bindings call it automatically now
   (though I plan to switch to the network package, where it's a different
   story).

 * Remove OverlappedRec structure size and alignment tests.  This package
   doesn't make assumptions based on those tests, and these properties
   changed when I added an alive field to OverlappedRec.
IOCP.Manager: tweak comment to squash Haddock syntax error
IOCP.Manager: embed ERROR_IO_PENDING check into withOverlapped
Add Network.Socket.Windows, with connect implemented except for implicit bind
Network.Socket.Windows: fix withOverlapped_ to report received error code, rather than calling GetLastError in the current thread
Add lab/connect.hs
Network.Socket.Windows.connect: implement implicit bind step
lab/connect.hs: remove bind before connect

This should work, but the second connect fails with
"thread blocked indefinitely in an MVar operation".
Network.Socket.Windows.connect: relinquish MVar before calling bind