QML colour pickers
Note: this project is not maintained. See these files for an alternative HSL colour picker that doesn't rely on private Qt API:
https://github.com/mitchcurtis/slate/blob/master/app/saturationlightnesspicker.h https://github.com/mitchcurtis/slate/blob/master/app/saturationlightnesspicker.cpp https://github.com/mitchcurtis/slate/blob/master/app/qml/ui/SaturationLightnessPicker.qml