Author: Shamim Rezaie
MDL-70818 mod_forum: implement activity_dates for the forum module
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e6a6b0819638b92e3de229a98512f886377b32ab
http://github.com/moodle/moodle/commit/e6a6b0819638b92e3de229a98512f886377b32ab
+ 3.11 en [activitydate:due,mod_forum]