Add ToggleGoWidget to __all__
Make is_sane a property of ToggleContainerWidget
Enable notification for DropdownWidgets
Define is_sane for SliceWidget and OverscanWidget
Whitespace fix
Improve definition of is_sane for ReductionSettings

Closes #25
Tie button color to sanity in RedcutionSettings
Fix problems with notification of ToggleContainerWidget by children

Closes #27
Remove debugging print statements
Factor color change of big toggle button out
Move clipping settings into a separate widget
Fix attribute naming bugs in ToggleMinMaxWidget
Calculate sanity sensibly for CombinerWidget

Closes #29