[Dcmlib] Segmented Palette Color support in GDCM

[Mathieu Malaterre]

I am glad to annouce that GDCM CVS now supports Segmented Palette
Color. User are now able to properly open and display image such as:
gdcm-US-ALOKA-16.dcm as found in gdcmData.

Only 16bits luts have been tested so far. If you have an example of
8bits Segmented Palette color, please try and report issues if any.

Thanks to Sebastien B. for data.

-- 
Mathieu