invertedAppearance and invertedControls properties for ctkDoubleSlider, ctkDoubleSpinBox and ctkSliderWidget
Merge branch 'slider-inverted-properties'

* slider-inverted-properties:
  invertedAppearance and invertedControls properties for ctkDoubleSlider, ctkDoubleSpinBox and ctkSliderWidget

Conflicts:
  ctkDoubleSpinBox.h
  ctkDoubleSpinBox.cpp
Merge branch 'slider-inverted-properties'

* slider-inverted-properties:
  invertedAppearance and invertedControls properties for ctkDoubleSlider, ctkDoubleSpinBox and ctkSliderWidget