WYSIWYG is not adjusted, when someone else in mult-user mode edits a segment

To reproduce

• open a task with user A in browser A
• open the same task for simultaneous editing with user B in browser B
• edit and save a segment with user A
• now the segment gets updated immediately for user B in the segment table, but the WYWIWYG is not updated as well, as it should be.

In addition to this fix, whenever users add,remove or edit annotation, all other users should get this change.