Add ability to enter terminator char for W send_cmd_rx so one can do 'W FA; ;' without a timeout needed

doc/man1/rigctl.1

@@ -1131,8 +1131,8 @@ option above, will terminate each command string sent to the radio.  This
 character should not be a part of the input string.
 .
 .TP
-.BR W ", " send_cmd_rx " \(aq" \fICmd\fP\(aq " " \fInbytes\FP
-Send a raw command string to the radio and expect nbytes returned.
+.BR W ", " send_cmd_rx " \(aq" \fICmd\fP\(aq " " \fI[nbytes or terminator char\FP
+Send a raw command string to the radio and expect nbytes returned or the terminator char (e.g. ;).
 .IP
 This is useful for testing and troubleshooting radio commands and responses when
 developing a backend.  If the # of bytes requested is <= the number actually returned no timeout will occur.

tests/rigctl_parse.c

@@ -4891,6 +4891,7 @@ declare_proto_rig(send_cmd)
             ++rxbytes;  // need length + 1 for end of string
             eom_buf[0] = 0;
         }
+        if (arg2[0] == ';') eom_buf[0] = ';';
 
         /* Assumes CR or LF is end of line char for all ASCII protocols. */
         retval = read_string(&rs->rigport, buf, rxbytes, eom_buf,