No possibility to delete or deactivate semester entry at management

Within the Management of semester terms for courses it is not possible to "delete" or "deactivate" (past) semester terms. For course-autors, this leads to an sprawling list of course terms in the drop-down menu on the course info-page.

The solution is to hide terms from the past in the drop down. The drop down should only show the following semester terms:

• all terms where the end date is in the future
• the currently selected term, even when the end date is in the past