BUG: 0003847 create subseries based on image orientation in DICOM

Because the image orientation patient value can include a
comma, the logic to track the distinct values in a collection
of files failed to recognize different orientation values.
This led the only available loading option in slicer being one
with a mix of orientations, leading to incorrect geometry.
This fix allows the plugin to generate independent loadables
for each orientation, thus removing the incorrect behavior.

The issue remains that the loadable with the geometry warning
is still the highest confidence loadable which could lead
to errors. Will address that independently.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23696 3bd1e089-480b-0410-8dfb-8563597acbee