* Fixes#243 - Adds the fields 'intro' and 'introformat' in the attendance table.
This is done according to https://docs.moodle.org/dev/Activity_modules#install.xml
* Added 'intro' field. If not empty it will add a header (title + intro) in the view page and will be displayed in manage and report pages.
Using the Moodle core standard_grading_coursemodule_elements() function to show the grade section in the attendance module settings.
Starting from version 2.9.x this includes the gradepass feature, that permits to show, in gradebook report, the percentage of attendance in green if the grade is greater/equal than the gradepass value, otherwise is shown in red.
Dan Marsden
Daniel Thee Roperto
Lihi Dor
Paolo Tramonti
Artem Andreev
Luis Ramon Lopez