Reconsider lookup precedence hierarchy in QML

The fact that types rank above properties makes it hard to address value types. If we made them generally addressable, they would shadow properties and break code. Therefore, we now have "pragma ValueTypeBehavior: Addressable".

If types ranked below properties, we wouldn't have this problem, but we'd have to decide where exactly in the context/scope hierarchy we'd put them. If we put them on the very bottom, then context properties in any parent context or scope properties in any outer scope would shadow types. Such a thing would be rather unpredictable.