Author: Dongsheng Cai
MDL-71674 editor_atto: more assessible errors
http://git.moodle.org/gw?p=moodle.git;a=commit;h=1da0e42f0fde495a631d663655f39627b4f2bf8a
http://github.com/moodle/moodle/commit/1da0e42f0fde495a631d663655f39627b4f2bf8a
+ 3.10 en [imageurlrequired,atto_image]