Qtype: STACK: Upgrade YUI to AMD javascript.

amd/build/input.min.js

amd/src/input.js

classes/external.php

db/services.php

renderer.php

stack/input/ajax.php

version.php

...oodle-qtype_stack-input/moodle-qtype_stack-input-debug.js

.../moodle-qtype_stack-input/moodle-qtype_stack-input-min.js

...uild/moodle-qtype_stack-input/moodle-qtype_stack-input.js

yui/src/input/build.json

yui/src/input/js/input.js

yui/src/input/meta/input.json