MDL-46308 qformat_xml: fix import of broken calculated questions.

Questions like this should not exist, of course. But they do, so we
should avoid generating errors in this case.
MDL-37401 mod_scorm : autocommit for scorm
MDL-46660 muc: add env check to memcache driver
MDL-46748 MathJax filter: Make misconfigured mathjax url less "fatal" for Atto.
MDL-46748 MathJax filter: Update setting default for https cdn url.
MDL-45780 editor_atto: Update the textarea more often

This change updates the frequency of the textarea update to additionally
update it:
* on keypress; and
* on content paste.
MDL-45780 mod_quiz: Autosave should listen for textarea:change events too
Merge branch 'MDL-46748-master' of git://github.com/damyon/moodle
MDL-35984 grade: Add behat tests for grade aggregations
MDL-35984 grade: Recalculate min/max for sum of grades when hidden grades are involved.
MDL-35984 Grades: Fix deprecation of grade_category::aggregate_values
Merge branch 'MDL-35984-master' of git://github.com/damyon/moodle
Merge branch 'wip_MDL-46692_m28_forum' of git://github.com/skodak/moodle
Merge branch 'wip-MDL-30668-master' of git://github.com/marinaglancy/moodle
Merge branch 'MDL-45759-master' of git://github.com/andrewnicols/moodle
MDL-43740 core_grade: Thanks for Robert Russo for the patch. Removed the ability to set manual grade items to grade type "None"
Merge branch 'MDL-46688' of git://github.com/timhunt/moodle
Merge branch 'master_MDL-44015' of https://github.com/greg-or/moodle-mod_assign
Merge branch 'MDL-46496-master' of git://github.com/andrewnicols/moodle
Merge branch 'MDL-45932-master' of https://github.com/StudiUM/moodle