Prviously ITK exceptions could be uncaught, by the vtkITK readers
and instead would be caught by the slicer application event
loop, which led to a dialog warning users of unstable conditions
and suggesting restart.  But usually these were really just
anticipated failure modes of file reading that were completely
recoverable.

This change catches these exceptions at the vtkITK layer and maps
them to vtkErrorCodes that can be checked at the reader level
to give a more controlled user experience.

From: Steve Pieper <pieper@isomics.com>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@26119 3bd1e089-480b-0410-8dfb-8563597acbee