BUG: Turn off projections when annotations are deleted

Projections of annotations were not deleted with annotation.
This fix ensure the widget representing an annotation's projection is
deleted when the corresponding annotation is deleted.

Partially fixes #3214

From: Laurent Chauvin <lchauvin@bwh.harvard.edu>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22176 3bd1e089-480b-0410-8dfb-8563597acbee