Add default constructor for UdpSocket

- Default UdpSocket constructor binds to 0.0.0.0:0

inc/udpsocket.hpp

@@ -35,6 +35,13 @@ private:
 
 public:
 
+    /**
+     * @brief Create a UdpSocket that will be bound to Ipv4 0.0.0.0 and the 
+     * port 0. This will use a random free port and is useful for sending 
+     * only.
+     */
+    UdpSocket();
+
     /**
      * @brief Create a UdpSocket that will be bound to the local address and 
      * port that is specified in the SockAddr. 

src/udpsocket.cpp

@@ -7,6 +7,10 @@
 #include <poll.h>
 
 
+UdpSocket::UdpSocket()
+    : UdpSocket{"0.0.0.0", 0}
+{ }
+
 UdpSocket::UdpSocket(SockAddr _local)
     : local{_local}, sockfd{0}
 {