Merge branch 'dev' of https://github.com/maths/moodle-qtype_stack into proof-builder

adminui/index.php

amd/build/stackjsvle.min.js

amd/build/stackjsvle.min.js.map

amd/src/stackjsvle.js

corsscripts/cors.php

corsscripts/stackjsiframe.js

db/install.php

db/upgrade.php

doc/en/AbInitio/Authoring_quick_start_1.md

doc/en/Authoring/JSXGraph.md

doc/en/Authoring/Multiple_choice_questions.md

doc/en/Authoring/Testing.md

doc/en/Authoring/Tidy_Tool.md

doc/en/CAS/Validator.md

doc/en/Developer/Development_track.md

doc/en/Maintaining/index.md

doc/en/Topics/Propositional_Logic.md

lang/en/qtype_stack.php

question.php

questiontestedit.php