KinokoType should be scoped within ObjectKinoko

[malleoz]

KinokoType differentiates between light and dark variants of mushrooms. Right now it's defined outside of ObjectKinoko, which means that it's exposed to the Field namespace and thus shows up in the Doxygen documentation for the namespace overview: https://vabold.github.io/Kinoko/docs/html/namespaceField.html

We should move this definition under the protected section of ObjectKinoko.

[malleoz]

This is required because ObjectKinokoNm does not inherit from ObjectKinoko.