Improve a method name, and add missing comments.

locallib.php

question.php

renderer.php

stack/mathsoutput/mathsoutput.class.php

stack/mathsoutput/mathsoutputbase.class.php

stack/mathsoutput/mathsoutputfilterbase.class.php

stack/mathsoutput/mathsoutputmathjax.class.php

stack/mathsoutput/mathsoutputmaths.class.php

stack/mathsoutput/tests/mathsoutputmathjax_test.php

stack/mathsoutput/tests/mathsoutputmaths_test.php

stack/mathsoutput/tests/mathsoutputtex_test.php