1. Split the question_attempt tests into one class per file.
2. Imporve the API to give tests more control, and to test more of the
important code. Some of this is not used here, but it is about to be.
1/ type/match/tests/walkthrough_test.php - tests are failing randomly, looks like some weird randomisation is going on there - see TODOs
2/ type/multianswer/tests/upgradelibnewqe_test.php contains invalid expected value - see TODO