Author: Khoa Nguyen Dang
MDL-73874 Questions: Add new validation for Drag and drop into text
http://git.moodle.org/gw?p=moodle.git;a=commit;h=81e782860061f6a205d2688738da73168997060e
http://github.com/moodle/moodle/commit/81e782860061f6a205d2688738da73168997060e
+ 3.11 en [errorlimitedchoice,qtype_ddwtos]