Existing leaning resources should still work (display, copy, use in course,...)

OO-3304: Quality generator for curriculum elements should generate data collection right before its start date. Refactorings.

And implements back button in curriculum management site

Move the zoom action to the dedicated link, adn replace with a classic
select the click on title and identifier for curriculums, organisations
and taxonomy. Implements an open all / close all actions for tree table.
Add a root crumb for organisations and curriculums.

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

- minimum number of lectures

In the curriculum view, remove the specialized columns for repository
entries and merge them with the ones for curriculum elements, implements
activation for the selected curriculum

- maximum number of lectures
- start survey after last lecture block