Fix the NPE if a single page is used to structure tests or assessment
course elements

Set the envelop-from from reply-to if smtp.from is not defined in
configuration (patch D. Haag)

To retrieve the min. score, max. score and the cut value, double check
if the resource is really based on QtiWorks otherwise fallback to the
old configuration. Fix an issue in statistics where the max. score and
cut value are retrieve from the wrong place. Cache the min. score and
max. score in the results list of the course assessed identities to
prevent reloading the values for every user.

Show every rubric block of every parent sections of an assessment item
with its own box that the user can hide and show. Add the rubrics in the
result reports. In the section summary of the results report, don't show
section without score and items

Refactor the valdiation of the selected folder in the folder course
element

and an other user deleted the item in the meantime.