Creates a new connection abstraction structure. The argument usually one of
either NETCONN_TCP or NETCONN_UDP,
yielding either a TCP or a UDP connection. No connection is established by
the call to this function and no data is sent over the network.
For more advanced use, it is also possible to specify different connection
types: NETCONN_UDPLITE, NETCONN_UDPNOCHKSUM
or NETCONN_RAW.