Author: Sara Arjona
MDL-80461 courseformat: Deprecate unused strings for topics and weeks
http://git.moodle.org/gw?p=moodle.git;a=commit;h=0c716122940bae9579116a14147535b8b14546c9
http://github.com/moodle/moodle/commit/0c716122940bae9579116a14147535b8b14546c9
+ 4.4 en [cannotmarktopic,core_error]
+ 4.4 en [unknownhelp,core_error]
+ 4.4 en [markedthistopic,core]
+ 4.4 en [markthistopic,core]