fixed bug that using poll-type transfers in testable mode could sometimes lead to stalled tests or assert failures.

Cache accessors obtained through TestFacility::getScalar() and TestFacility::getArray() by the application test code, to avoid the loss of the current value if a decorated accessor is obtained again.

detect stalled tests and print a list of variables which contain data not processed by the application

- updated the tests for the testable mode and test the TestFacility class there as well