Fixed catastrophic memory leak in client

Whenever a server would be stopped while the clients were connected to
it, the for loop handling the messages received by the server would
start a feedback loop as no more data could be read from "conn", thus
spawning an infinite number of byte arrays and crashing my laptop

cmd/ui.go

@@ -35,7 +35,11 @@ func listener(g *gocui.Gui, conn net.Conn) {
 	}
 	for {
 		reply := make([]byte, 2048)
-		conn.Read(reply)
+		_, err := conn.Read(reply)
+		if err != nil {
+			g.Close()
+			log.Fatalf("Server closed connection\n")
+		}
 
 		fmt.Fprintln(chatbox, string(reply))
 		termbox.Interrupt()