Author: Simey Lameze
MDL-5311 qtype_multichoice: add clear my choice option
http://git.moodle.org/gw?p=moodle.git;a=commit;h=f6a778497e29e2828bdd73600209f8e7ea07bbde
http://github.com/moodle/moodle/commit/f6a778497e29e2828bdd73600209f8e7ea07bbde
+ 3.7 en [clearchoice,qtype_multichoice]