Bug-fix: when using Telnet, we would *always* send the terminal type

(if the server supported the option), as "ANSI". Now, if the current cterm
emualation is PETASCII [sic], or ATASCII, send "PETSCII" or "ATASCII"
instead.

Now this brings up a couple of discussion points:
1. Should that default Telnet term-type be "ANSI-BBS" (or "ansi-bbs") instead?
2. Similarlly, RLogin connections *always* send the term-type as "ansi-bbs" -
   I think a similar change is needed in rlogin.c to be technically correct,
   but we should probably be consistent about how SyncTERM in ANSI-BBS emulation
   mode identifies itself ("ANSI", "ANSI-BBS", or "ansi-bbs").
3. If there is terminal type advertised via SSH, that probably needs addressing
   as well.

src/syncterm/telnet_io.c

@@ -6,6 +6,7 @@
 #include <string.h>
 
 #include "term.h"
+#include "cterm.h"
 
 #include "genwrap.h"
 #include "sockwrap.h"
@@ -158,11 +159,21 @@ BYTE* telnet_interpret(BYTE* inbuf, int inlen, BYTE* outbuf, int *outlen)
 					/* sub-option terminated */
 					if(option==TELNET_TERM_TYPE && telnet_cmd[3]==TELNET_TERM_SEND) {
 						char buf[32];
-						int len=sprintf(buf,"%c%c%c%cANSI%c%c"
+						const char *termtype = "ANSI";
+						switch(cterm->emulation) {
+							case CTERM_EMULATION_PETASCII:
+								termtype = "PETSCII";
+								break;
+							case CTERM_EMULATION_ATASCII:
+								termtype = "ATASCII";
+								break;
+						}
+						int len=sprintf(buf,"%c%c%c%c%s%c%c"
 							,TELNET_IAC,TELNET_SB
 							,TELNET_TERM_TYPE,TELNET_TERM_IS
+							,termtype
 							,TELNET_IAC,TELNET_SE);
-						lprintf(LOG_INFO,"TX: Terminal Type is ANSI");
+						lprintf(LOG_INFO,"TX: Terminal Type is %s", termtype);
 						putcom(buf,len);
 						request_telnet_opt(TELNET_WILL, TELNET_NEGOTIATE_WINDOW_SIZE);
 					}