Each default (and only supported) CPAppearance now have an associated
theme state. As the appearance is correctly propagated in CPViews
hierarchy, it is now possible to have dark controls when the an
ancestor view has a dark appearance.
Added automated tests
This patch adds the `CPAppearance` class and uses it where needed.
There is nearly no impact, but in `_CPPopoverWindowView` where the
`CPPopoverAppearance` needs to be converted to a `CPAppearance` object
nib2cib support has also been added.
*This patch brings no new functionality.*
David Richardson
Antoine Mercadal