plagiarism_turnitin: Allow late submissions if cutoff date not enabled

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
mod_turnitintooltwo: Fix image references in style rules

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
plagiarism_turnitin: Fix image references in style rules

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
plagiarism_turnitin: Fix errors screen error caused by file absence.
plagiarism_turnitin: Style TII ULA link to look like an error/warning

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
plagiarism_turnitin: Only update grades if grading scheme is numeric

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
mod_turnitintooltwo: Fix access to grademark and originality reports.

When quick grading is enabled, access to grademark and originality reports
was not possible because of form conflict.
plagiarism_turnitin: Fix treatment of arrays as objects

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
plagiarism_turnitin: Don't show config options disabled at site level

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
plagiarism_turnitin: Include lib/gradelib.php for grade_update()

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>