Check for user disconnection in CheckTerminate()

A user disconnecting while running tw2 would just result in an infinite loop
checking node status and waiting for the user's allowed time to run out (which
may never happen) or for the server to be locally terminated.

This has been happening for years on Vertrauen. Finally now I see why.

xtrn/tw2/input.js

@@ -38,7 +38,7 @@ function CheckTime()
 
 function CheckTerminate()
 {
-	if(js.terminated)
+	if(js.terminated || !bbs.online)
 		exit(0);
 }