BUG: disable alternate color editors

The color module was just collapsing the color table and
continuous color transfer viewer/editors when the other type
of node was active. User feedback showed this to be confusing
as valid looking data was visible if the sections were
expanded. This change disables the invalid editor on
selection of a color node.

Issue #3573


git-svn-id: http://svn.slicer.org/Slicer4/trunk@23117 3bd1e089-480b-0410-8dfb-8563597acbee