Systematically deploy variants: fix to issue #1011.

deploy.php

doc/en/Authoring/Deploying.md

doc/en/CAS/Random.md

doc/en/CAS/Systematic_deployment.md

doc/en/Developer/Development_track.md

doc/en/Developer/Future_plans.md

doc/meta_en.json

lang/en/qtype_stack.php

question.php

questiontestrun.php

stack/cas/cassession2.class.php

stack/cas/security-map.json

tests/castext_test.php