ENH: Create color table for labelmap when exporting segmentation

When the binary labelmap from a segmentation was exported to a labelmap node, the colors were not propagated. Now a color table node is created (or just updated if it existed and it was user type) for the labelmap, and so the labels have the same colors as the segments they came from.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25580 3bd1e089-480b-0410-8dfb-8563597acbee