Telnet specials menu was not being reinstated after a session was restarted in

the same window (Windows version only).

Policy change: it's now the backend's responsibility to call
update_specials_menu() at the start of a session (or whenever it feels ready),
if it has any special commands. Otherwise the menu won't be displayed.

[originally from svn r4649]

telnet.c

@@ -762,6 +762,11 @@ static const char *telnet_init(void *frontend_handle, void **backend_handle,
      */
     telnet->in_synch = FALSE;
 
+    /*
+     * We can send special commands from the start.
+     */
+    update_specials_menu(telnet->frontend);
+
     return NULL;
 }