MDL-47053 gradereport_grader: Add a floating Footer Title cell

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.
MDL-47025 gradereport_grader: Removing highlight feature

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.
MDL-47026 gradereport_grader: Removing the tooltips

They are not serving the same purpose as the one they had before,
and they were overlapping with the content of the cell. Positioning
them somewhere else made them more confusing than helpful.

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.
MDL-47063 gradereport_grader: Styles applied for overridden grades
MDL-47028 gradereport_grader: Add floating headers for other cells.

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.
MDL-46936 gradereport_grader: Restore AJAX editing to gradereport

Removed id argument from AJAX code, no longer supplied.

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.
MDL-47124 gradereport_grader: Update row/column sizes when showing/hiding quickedit fields

This makes use of Global YUI events to trigger the resized event handler.

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.
MDL-46658 gradereport_grader: Make page CSS more specific
MDL-47353 gradereport_grader: Fix header offset logic for floating headers

This is necessary for themes with non-fixed navbars to work with the
grader report, otherwise headers will be hidden.

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.
MDL-44536 workshop: Fix missing phpDoc for user report callbacks
MDL-31936 workshop: Initial implementation of the course reset support
MDL-47299 libraries: upgrade PHPMailer to 5.2.8
MDL-31936 workshop: Add unit tests for the workshop reset
MDL-31936 course: Add missing file level docblock to the reset_form.php

Not related to the issue itself but spotted while working on the
workshop reset feature.  Assigning copyleft holder to Petr as the
original author of the file.
MDL-31936 workshop: Fix overall feedback content processing order

This is unrelated to the issue but was spotted while testing it. The order of
format_text() and file_rewrite_pluginfile_urls() was incorrect and threw
debugging message. Fixed now.
MDL-31936 workshop: Delete attachments on record removal

The methods workshop::delete_submission() and workshop::delete_assessment() did
not delete files (embedded and attachments) associated with the given
submission or assessment. This is fixed now.

Additionally, the delete_assessment() method now cleans-up records from the
table workshop_grades, too. This internal workshop API still does not give
workshop subplugins a chance to clean up their data, should they store them in
their own tables instead of the workshop_grades one. This should be improved in
the future yet.
MDL-31936 workshop: Add more options to the course reset form

This is built upon original work by Michael Hughes. We now have separate
settings for deleting workshop submissions, assessments and for resetting the
workshop phase.
MDL-31936 workshop: Generator able to create submissions and assessments

This is a basic implementation of the actual content generation in the workshop
generator. Note the we do not generate actual grading form data (which is what
the grading strategy plugins would do), just their results.
MDL-47062 Grades: Add an upgrade step to warn about changes in upgrade.

Puts a notice on the grader report about the change in aggregation method
from "Sum of grades" to "Natural".

Part of: MDL-46576
MDL-47520 core_grades: added CSS classes to the setup page

Part of: MDL-46576