Ok, I'm convinced... initiate some telnet negotation

- Attempt to suppress go aheads in both directions.
- Attempt to set binary mode in both directions
- Request the remote echos

These express the assumptions that SyncTERM always makes, so it's
a good idea to tell the remote this.  For systems that don't like
this, there is the Raw "protocol".

src/syncterm/conn_telnet.c

@@ -151,6 +151,14 @@ telnet_connect(struct bbslist *bbs)
 
 	_beginthread(rlogin_output_thread, 0, NULL);
 	_beginthread(rlogin_input_thread, 0, bbs);
+	// Suppress Go Aheads (both directions)
+	request_telnet_opt(TELNET_WILL, TELNET_SUP_GA);
+	request_telnet_opt(TELNET_DO, TELNET_SUP_GA);
+	// Enable binary mode (both directions)
+	request_telnet_opt(TELNET_WILL, TELNET_BINARY_TX);
+	request_telnet_opt(TELNET_DO, TELNET_BINARY_TX);
+	// Request that the server echos
+	request_telnet_opt(TELNET_DO, TELNET_ECHO);
 
 	if (!bbs->hidepopups)
 		uifc.pop(NULL);