Author: Jean-Michel Vedrine
MDL-63905 qtype_multianswer: validate imported questions
http://git.moodle.org/gw?p=moodle.git;a=commit;h=ffe4e082b089f75cad69ddb27a9a3243617dc748
http://github.com/moodle/moodle/commit/ffe4e082b089f75cad69ddb27a9a3243617dc748
+ 3.5 en [invalidmultianswerquestion,qtype_multianswer]