BUG: fixing fiducial projections

Turning them on for the first time was causing a null pointer crash in the
VTK 6 rendering pipeline. The glyph source hadn't been updated and the points
were undefined in the default circle glyph.

Also call the displayable manager superclass on scene close to ensure that the
fiducial projections are removed from the render window.

Issue #3821

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23668 3bd1e089-480b-0410-8dfb-8563597acbee