BUG #14288. Fixed LUT editor issues.

Due to incorrect order of setup methods, the vtkCompositeControlPointsItem
instance we ending up synchronizing the control points on LUT and Opacity
function. Fixed that. This was causing the bogus points to show up as reported
in the bug report.

Change-Id: I5bf2c92b20ea5e793b6896b3fef049c90281030f
Merge topic '14288_fix_lut_editor' into next

68feaab BUG #14288. Fixed LUT editor issues.