This class would belong more appropriately within the 'user' API
(core_user) instead of within the 'core' API, since it is
directly related to user data.
Since the class has only just been added to Moodle, now is a good
time to move it.
Use the current filters and sorting on the user grading table in the single
page grading app when it is possible.
This replaces the popover used to configure the filters to one that closely matches the
one from the grading table. It supports standard filters, workflow filters and allocated marker filters.
It will also support group filtering and suspended user filtering but we don't show the controls for those in
the single grading page.
Luca Bösch