BUG: Prevent SliceViewAnnotations from dividing by zero

It can happen in some cases and it is important to recover gracefully, not just get a long python error.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23742 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: #3873 lingering vtk5 code broke module

Need to use the newer pipeline calls for vtk 6

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23743 3bd1e089-480b-0410-8dfb-8563597acbee