OO-1604: fix the red screen, fix the stupid warning, wording for the editors, create the tasklist object by import and copy of courses

OO-991: fix an issue with enable/disable in tabbedpane component, add embedded editor for tasks / solutions, add author / uploader in a lot of places, wording for relatives dates in workflow

OO-991: add some cancel buttons, show the choosed tasks in the list of coached groups and identities and other fixes

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