Author: Luca Bösch
MDL-58411 qtype_essay: Add file type validation in essay question type
http://git.moodle.org/gw?p=moodle.git;a=commit;h=94cb5a662a94bd7560a3bb9a703bd93f8d3b6558
http://github.com/moodle/moodle/commit/94cb5a662a94bd7560a3bb9a703bd93f8d3b6558
+ 3.5 en [acceptedfiletypes,qtype_essay]
+ 3.5 en [acceptedfiletypes_help,qtype_essay]
+ 3.5 en [nonexistentfiletypes,qtype_essay]