Sample response evaluation renders tags

Sample response evaluation now renders html instead of showing raw tags. Plus other fixes

Moodle 5.1 Compatibility

Confirmed compatibility with Moodle 5.1 by running automated tests.

Updates from Moodle.org Plugin review

Minor updates from feedback from Moodle.org Plugin review

First release for moodle.org

First release for submission to moodle.org plugins repository