OO-1873: replace the listing of booking by a native query optimized for our standard setup, replace the .hbm.xml with annotations, add more fetching overall

OO-1881: the isAssessmentMode expert rule is now dependent of the user which open the course and not only from the state of the course

OO-1882: in assessment mode editor, highlight the right field if course elements options are selected but not the course elements

OO-1879 implement context help using confluence for course help SPI. Course help only used for main manual link.

OO-1876: don't break the recursion for the project broker course element, don't take it as assessable, but takes its children elements