Author: Dan Poltawski
MDL-48846 filter: Stop reffering to invalid moodle.org/download/mimetex
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8252dfbd00ee3fa1f5d2ea0786e0c6169be11c24
http://github.com/moodle/moodle/commit/8252dfbd00ee3fa1f5d2ea0786e0c6169be11c24
+ 3.4 en [mimetexisnotexist,core_error]