Author: Tim Hunt
MDL-20636 Conversion of the missingtype question type.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=94814340192f0b483fae4ae41cc334715d0494cb
http://github.com/moodle/moodle/commit/94814340192f0b483fae4ae41cc334715d0494cb
+ 2.1dev en [addingmissingtype,qtype_missingtype]