Author: Mark Nelson
MDL-40913 core_message: created 'message_read' event
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5b09190975873d40d100186b3b48caccca8bf306
http://github.com/moodle/moodle/commit/5b09190975873d40d100186b3b48caccca8bf306
+ 2.7 en [eventmessageread,core_message]