StackView needs custom activateSuperviewHuggingConstraints when using custom stack view spacing #49

Perhaps there is another intended way to do this, but if I set the .stackView.spacing property, the top of the stack view is still flush with the AutoScrollView instead of offset by the spacing amount which makes the layout look wrong. It looks like simply passing the stack view spacing property as a edge inset to activateSuperviewHuggingConstraints in commonInit() on line 130 of StackViewContainer might do the trick