ENH: colortable now is not possible to select when not appropriate

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21584 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fixed bug 2746, cleaned header file

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21585 3bd1e089-480b-0410-8dfb-8563597acbee