Currently, TLS is only supported in TCP via programmatic configuration: the SocketFactory has to be replaced with one which creates SSLSockets etc.

Goal: provide XML configuration that creates a socket factory supporting TLS. This is similar to what is done in SYM_ENCRYPT.

To support TLS in TUNNEL, we probably have to place the attributes into TP. However, UDP and TCP_NIO2 would throw an exception if set / or ignore them and log a warning.