Teachers can now choose the actual grading evaluation method to use
during the grading evaluation phase. The workshopeval_best is still used
as the default one (this may be made configurable later, although there
is no big benefit of it).
The method user_picture::fields() was not available when these SQL
statements were originally written. Now instead of hard-coding the list
of returned fields, the user_picture is asked for the list.
Together with this change, methods workshop::get_submission_by_id()
and workshop::get_submission_by_author() now return the information
about the user who provided the feedback and overwrote the grade.
While working on the new capability to view authors of published
submissions, I realized that published submissions are correctly listed
(implemented in 00bc77ee) but they can't be viewed by submission.php.
This patch fixes submission.php so that it allows to view published
submissions.
Also, I noticed that when the workshop is closed, the submissions that
were assessed by the user are not listed (as they were in the previous
phases) but submission.php provides access to them correctly. So I added
a code that lists assessed submissions in the closed phase.
Important change: teacher's assessments of example submissions (now
known as "reference assessments") are now displayed to students after
they assess example submission.
