Fix to issue #333.

bulktest.php

bulktestall.php

doc/en/CAS/Matrix.md

doc/en/Developer/Development_track.md

doc/en/Developer/Running_question_tests_other_site.md

lang/en/qtype_stack.php

question.php

questiontestrun.php

questiontype.php

stack/bulktester.class.php

stack/maxima/assessment.mac

stack/potentialresponsetree.class.php

tests/helper.php

tests/question_test.php