AbstractSlider and Slider: - make scheme() a full-weight property, dual with ticks():   when ticks is operated, scheme() is nulled, and likewise when   scheme is written to, ticks() is nulled. - min/max/increment automatically regenerate ticks if scheme is defined - try to fit text labels within bound of the widget, so leftmost and   rightmost labels are visible fully
AbstractSlider and Slider:
- make scheme() a full-weight property, dual with ticks():
  when ticks is operated, scheme() is nulled, and likewise when
  scheme is written to, ticks() is nulled.
- min/max/increment automatically regenerate ticks if scheme is defined
- try to fit text labels within bound of the widget, so leftmost and
  rightmost labels are visible fully

run4flat/Primo,run4flat/Primo