The patch introduces a new script templates.php that allows to search
for a previously shared form (template) and re-use it.
The patch also modifies the preview rendering of grading forms. Now
plugins are responsible for rendering the form itselft, without any
headers, descriptions etc (we need to embed the form preview into
various places so the caller looks after the frame).
There is a new API method get_definition_copy() that is expected to
return the definition structure as if the form was written from scratch
via the editor. Such a prepared structure is passed to
a controller's update_definition() method in the new target area.
The same mechanism will be used for copying definitions from a shared
area to a normal gradable area.
The user is sent to the new grade/grading/manage.php screen when an
advanced grading method is set in the activity mod form or via the
settings block.
The screen is supposed to (1) let the user change the currently active
grading method, (2) open the editor for the selected method, (3) create
new form from a template (4) display a preview of the form.
