Notification of string changes

Author: Thanh Le
MDL-35792 question preview: way to update options without restarting.
It is useful, and possible, to update the display options without
restarting the question. You now only have to restart if you are
changing the maximum mark or the behaviour.


http://git.moodle.org/gw?p=moodle.git;a=commit;h=599cc731e360993672dba702740d8aef4a6109e9
http://github.com/moodle/moodle/commit/599cc731e360993672dba702740d8aef4a6109e9

+ 2.5 en [attemptoptions,core_question]
+ 2.5 en [displayoptions,core_question]
+ 2.5 en [updatedisplayoptions,core_question]