Add udpflow sample application

This is a very simple application which forks 2 threads, one sending
messages to a port, another one receiving (and discarding) them.

The application should be built using the threaded RTS. Consider using
2 capabilities upon execution (+RTS -N2).

network-conduit/udpflow.hs

@@ -0,0 +1,34 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+-- Build using threaded RTS
+
+import Data.Conduit
+import Data.Conduit.Network.UDP
+import qualified Data.Conduit.List as CL
+
+import Control.Concurrent (forkIO, threadDelay)
+import Control.Monad (forever)
+import Data.ByteString.Char8 ()
+import Network.Socket (addrAddress)
+
+localhost :: String
+localhost = "127.0.0.1"
+port :: Int
+port = 4000
+
+receiver :: IO ()
+receiver = do
+    sock <- bindPort port (Host localhost)
+    sourceSocket sock 4096 $$ CL.mapM_ (\_ -> return ())
+
+sender :: IO ()
+sender = do
+    (sock, addr) <- getSocket localhost port
+    CL.sourceList (repeat ("abc", addrAddress addr)) $$ sinkSocket sock
+
+main :: IO ()
+main = do
+    forkIO receiver
+    forkIO sender
+
+    forever $ threadDelay $ 1000 * 1000 * 10