Code tidy and docs tidy.

adminui/caschat.php

adminui/equivdemo.php

adminui/healthcheck.php

adminui/subscripts.php

doc/en/Authoring/Answer_tests.md

doc/maintenance.php

question.php

questiontype.php

renderer.php

stack/cas/caserror.class.php

stack/cas/castext2/block.factory.php

stack/cas/connector.linux.class.php

stack/cas/keyval.class.php

stack/cas/parsingrules/998_security.filter.php

stack/input/equiv/equiv.class.php

stack/input/factory.class.php

stack/input/inputbase.class.php

stack/input/matrix/matrix.class.php

stack/prt.class.php

tests/castext2_test.php