Add API parity stubs for UDP sockets/TCP streams (#174)

These are no-ops in turmoil, but having these available
minimizes the amount of caller code that needs to change.

src/net/tcp/stream.rs

@@ -127,6 +127,12 @@ impl TcpStream {
             },
         )
     }
+
+    /// Has no effect in turmoil. API parity with 
+    /// https://docs.rs/tokio/latest/tokio/net/struct.TcpStream.html#method.set_nodelay
+    pub fn set_nodelay(&self, _nodelay: bool) -> Result<()> {
+        Ok(())
+    }
 }
 
 pub(crate) struct ReadHalf {

src/net/udp.rs

@@ -13,7 +13,7 @@ use crate::{
 use std::{
     cmp,
     io::{self, Error, ErrorKind, Result},
-    net::SocketAddr,
+    net::{Ipv6Addr, SocketAddr},
 };
 
 /// A simulated UDP socket.
@@ -299,6 +299,18 @@ impl UdpSocket {
 
         Ok(())
     }
+
+    /// Has no effect in turmoil. API parity with 
+    /// https://docs.rs/tokio/latest/tokio/net/struct.UdpSocket.html#method.set_multicast_loop_v6
+    pub fn set_multicast_loop_v6(&self, _on: bool) -> Result<()> {
+        Ok(())
+    }
+
+    /// Has no effect in turmoil. API parity with 
+    /// https://docs.rs/tokio/latest/tokio/net/struct.UdpSocket.html#method.join_multicast_v6
+    pub fn join_multicast_v6(&self, _multiaddr: &Ipv6Addr, _interface: u32) -> Result<()> {
+        Ok(())
+    }
 }
 
 fn send_loopback(src: SocketAddr, dst: SocketAddr, message: Protocol) {