Yet another tweek reflecting the removal of GUI redirects

CVWidget2D: set CV.viewDictionary[Slider2D].props and
CV.viewDictionary[RangeSlider].props rather than
CV.viewDictionary[QSlider2D].prop and
CV.viewDictionary[QRangeSlider].prop if Main.versionAtLeast(3, 7)

Signed-off-by:  <st9fan@gmail.com>