Gapfill 1.8 Release Notes

Fixed a bug by adding checking for initialisation of array values that could cause the display of error messages when taking exams. Discussed here https://moodle.org/mod/forum/discuss.php?d=314487#p1274939. Thanks to Ellen, Al and others for the feedback on this.

Added a value in settings so the default for case sensitive can be set, i.e. make the questions case sensitive box be checked by default.

Updated the export of xml code so it adds information on the version of the Gapfill plugin and the version of Moodle that ran the export. This data can be useful for tracking down issues.

Small changes/clarifications to strings