BUG: 3084. Fixed multiple usability issues in ROI selection in Tractography Display module.
1. Changing Percentage Fibers Shown does not update display
2. Percentage Fibers Shown should update on mouse release not on drag
3. The ROI selection controls should be inactive until Fiber and ROI are selected to prompt users to select
4. Better name for ROI nodes needed
5. Tube slices do not show up on the newly created Fibers 

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21907 3bd1e089-480b-0410-8dfb-8563597acbee