Author: Simey Lameze
MDL-70782 course: add setting to show activity dates
Part of MDL-70817
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8b47f169266706602d75b0c93a271dd2026c747b
http://github.com/moodle/moodle/commit/8b47f169266706602d75b0c93a271dd2026c747b
+ 3.11 en [showactivitydates,core]
+ 3.11 en [showactivitydates_help,core]