Author: Adrian Greeve
MDL-39962 - Events: Replace the legacy event workshop_viewed
This also includes the abstract class course_module_viewed.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=d76a0eec399c91fa81cff64ace3857aac0abd33e
http://github.com/moodle/moodle/commit/d76a0eec399c91fa81cff64ace3857aac0abd33e
+ 2.6 en [workshopviewed,mod_workshop]