ENH: make the code compatible with VTK5
ENH: minor changes to file list handling

* make it explicit that only first file in the file list is considered
* remove derivedItems from loadable: processing of RWV does not result in
   creation of any new DICOM instances
ENH: simplify examine()

Use DICOMScalarVolumePlugin.examine() directly instead of duplicating the code.
ENH: minor modifications

* do not initialize DICOM attributes for patient information - some of this
   info is available via subject hierarchies, and some is not needed
* reorder the code that initializes subject hierarchy
Merge pull request #1 from fedorov/cleanup

Reorganization and cleanup