Author: Tim Hunt
MDL-27649 Convert the calculated question types to use the new variants mechanism.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=c014b989ba44b7e2bb0c02cdd19826ca2cee13c8
http://github.com/moodle/moodle/commit/c014b989ba44b7e2bb0c02cdd19826ca2cee13c8
+ 2.1dev en [questionvariant,core_question]