Deprecate PC.verify

Remove the PC.verify method in favour of a VerifyingVisitor.

Pc.verify is a typical method used in development, but not in a life environment. An analysis of the PC.verify usage shows, that the method is not called anywhere in the whole code base of Pico/Nano/Micro except for unit tests and decorator PCs.

Using the visitor pattern and our PicoVisitor we are able to provide the user with a VerifyingVisitor that has same capabilities and deprecate and later remove PC.verify to clean-up the API.