MDL-45560 report_log: Close sessions before download only

If the session is closed too early, then preferences made in the body of
the page will not be saved to the session.
MDL-45767: Fixed DB error when returning to course from external tool

The instance ID is not always returned from the external
tool provider.
Automatically generated installer lang files
Automatically generated installer lang files
MDL-45763 question Random qtype should use '0' or '1' question text.

Some time ago, it when from using '0' for no-subcategories to blank.
Change to properly define '0' or '1', update old questions, and make
sure to fix newly restored questions.
MDL-45804 mod_workshop: fixed objecttable specified for the submission_reassessed event
MDL-45714 backup: Less aggressive removal of old backup dirs

The old 4 hour standard was too aggressive and can cause backup files
to be removed while they were still in use. Now the same as cron,
1 week.
MDL-42782 usability: fix for extreme course page indenting
MDL-45634 editor_atto: Adding type button to toolbar buttons

This prevents the browser to assume that those buttons are submit
buttons. In which case the submit action was stolen and the form
could not be submitted pressing the 'enter' key.
MDL-45579 group: Prevent duplicate enrolment keys in course groups
MDL-45579 group: Behat tests to cover group enrolment key rules
MDL-45808 group: Observe the group key policy upon group creation
MDL-44501 mod_data: Only attempt to export files when a file exists.

The error only occurs when portfolios are enabled and there is only one field which is
a file field.
MDL-39726 backup: Move question files by context, not one at a time

Use question category contexts to send file to the file pool in bulk.
Questions are only restored in whole category chunks, so this is safe
to do.
MDL-44309 Administration - correcting inproperly assigned column classes in environment table
MDL-45870 mod_assign: Outcomes are saved for each group member
MDL-45761 assign Set inline comment format properly when plugin is empty

If a plugin says it is empty, skip it for for building the inline
comment.

If not format was found in any plugins, set to FORMAT_HTML, which is
the default for feedback anyways.
MDL-20154 questions: question_delete_question should not check perms

By Moodle convention, library functions should not implement permission
checks, they are to be handled by the invoking code.
Merge branch 'install_master' of https://git.in.moodle.com/amosbot/moodle-install
weekly release 2.8dev