Enable binary-transmit mode in server by default, disabling CR->CRLF expansion

Don't expand CR->CRLF when in binary mode that was requested locally
(option value is DO, instead of WILL), using new telnet_opt_enabled().

Request binary-transmit mode by default in Telnet server/answer mode.
Set ServerBinary=false in svdm.ini to disable.

This fixes the extra line-feeds in Telnet-server mode.