Feature net::UdpSocket connect, send+to, recv+from, etc.

[pinkforest]

Working on #17

Implements

• connect()
• send(), send_to()
• recv(), recv_from()
• set_ttl(), ttl()
• set_broadcast, broadcast()
• set, get, use timeouts
• dummy fn's set_nonblocking & take_error

Notes

• std UdpSocket connect has no connect timeout unlike lunatic host fn - as it's stateless unlike Tcp
• There does not seem to be peer_addr() host networking API call for connect()'ed UDP sockets ? should there be ?
• Networking API UDP peer_addr Missing lunatic#110
• std::UdpSocket peer_addr : https://doc.rust-lang.org/std/net/struct.UdpSocket.html#method.peer_addr
• Multicast & Peek not in host networking API

Moar Notes

• UdpSocket IPv6 addr bind accidentally called tcp_bind 😱 🤦‍♀️ - fixed it 😰 🥵
• As previous consider in future to refactor for addr in addr.to_socket_addrs() like std net's each_addr

[bkolobara]

That's awesome work @pinkforest. Thank you so much for the contribution!