Server-side only. Listens for incomming connections.
_Io_Listen($iPort, $sAddress = @IPAddress1, $iMaxPendingConnections = Default, $iMaxDeadSocketsBeforeTidy = 1000, $iMaxConnections = 100000)
| integer. Null + @error if error |
If `$iMaxDeadSocketsBeforeTidy` is set to `False`, you have to manually call `_Io_TidyUp` to get rid of dead sockets, otherwise the `iMaxConnections + 1` client that connects, will be instantly disconnected.