Currently it is not possible to select or avoid specific reader services when you use mitk::IOutils (e.g. in tests or commandline apps). Internally IOutils has a callback option but it is not accessible in the public interface an can only be used by inheritance (c.f. QmitkIOutils). There is currently no known reasoning for not allowing callbacks/dependency injection also in the public interface of IOutils.

Todos:

1. Allow public load functions to specify a callback. Default value is NULL (therefor same behaviour as now)
2. Implement a callback class that allows white listing (first hit on a whitelist is always used) and black listing (candidates on a black list are never used).