* Cleaned up unused Mod integrations other than for mods that are likely to be integrated soon.
* Introduced an easier Facade class to access mod integration abstractions (called Integrations).
* Removed the link between IntegrationType and integration abstraction. Integrations are now explicitly instantiated inside of IntegrationNode.
Removes the improper way to set itself into a public static non-final variable.
Removes the direct access to the IntegrationRegistry from AppEng. Will be added at some later point somewhere else for non-singleton access.
Constructor is set to package private to enable possible construction from unit tests. Are current not runnable sind it is currently tied to the FML Loader instance.