Expand TcpStream and UdpSocket options

[Thomasdezeeuw]

From the manual for setsockopt:

SO_KEEPALIVE    enables keep connections alive
SO_LINGER       linger on close if data present
SO_OOBINLINE    enables reception of out-of-band data in band
SO_SNDBUF       set buffer size for output
SO_RCVBUF       set buffer size for input
SO_SNDLOWAT     set minimum count for output
SO_RCVLOWAT     set minimum count for input
SO_SNDTIMEO     set timeout value for output
SO_RCVTIMEO     set timeout value for input