fixed lock-up when auto-testing tape which causes loop in game engine

It is possible to create endless loops in the game engine by using
recursive custom element properties. These endless loops are detected
and the user is notified by a request dialog about this problem to be
able to stop the running game. When auto-testing tapes on the command
line, answering a graphical request dialog is not possible, which
causes the program to hang.

This fix stops replaying the tape in this case (and skips the request
dialog), so auto-testing tapes can continue (with an unsolvable tape).