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.
Deprecates the old usage of the AEItemDefinitions via the direct method access of
* blocks()
* parts()
* items()
* materials()
and thus use the new re-direct via definitions().
All definitions are now initialized, no matter what. But SubItems, Items and Blocks are not registered, if by chance are disabled.
