ENH: move the User and File node types up to superclass
Support for user and file procedural color nodes requires that these
node types be moved into the color node superclass, not just defined
on the color table node.

Issue: 3573



git-svn-id: http://svn.slicer.org/Slicer4/trunk@23082 3bd1e089-480b-0410-8dfb-8563597acbee