OO-1873: replace the deepCopy (java serialization / deserialization ) of the test by a simple XML parsing on the content

OO-1873: reduce number of objects generated by some toString methods, optimize the normalizeFilename to prevent the creation fo 10 compiled regex patterns

OO-1873: for the XSLT transformation for QTI results, replace the synchronized transformer with templates, reduce the StringBuilder <-> String copy paste

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