OO-991: implements relative dates for assignment, submission and solution due dates, enhance the reminders rules engine to support them

OO-1544: better check of the validity of the last history point used in the "close" method of the course tab

no-jira: use javascript to fill the import textarea as copy/paste is not supported on the different browsers and platforms i want, add a selenium test which import an existing user and change its last name and password

OO-1539: add a timeout to the focus command, jQuery dialog focus something on its own and we must wait it is finished with it

OO-1542: copy the list of listeners and loop on the copy to prevent concurrent modification exception

OO-1540: the display name use to select the repository entry, add links for selection, removal and preview

OO-1541: select the user in the username column and the the next 2, action column now opens the visiting card, fix some wording issues

OO-1522: make the number of threads in the indexer pool configurable, set the priority of these threads the minimal

OO-1511: add more warnings if a course node is used by an assessment mode configuration, add warnings in the mode list adn edit mode panel if a course node cannot be found

OO-1537: authors can see and edit the business groups in their groups from the user management tool of the course