Author: David Mudrák
MDL-53240 filetypes: Introduce admin_setting_filetypes class
This new type of admin settings makes use of the filetypes browser but
for the admin settings.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8cf36e9c81a704c8dee90d0fef9402aec0eaf80e
http://github.com/moodle/moodle/commit/8cf36e9c81a704c8dee90d0fef9402aec0eaf80e
+ 3.4 en [filetypesnotwhitelisted,core_form]