Need to shut down the dynamic factory when it is not in use

[ywei]

Some dynamic factories in the program never have the shutdown() method called after their creation. That will cause the Java garbage collector to try to garbage collect some unreferenced dynamic factory, but since they are not deleted, the ValidityChecker class in CVC3 API will throw warnings. So it is better to make sure that every dynamic factory has its shutdown() method called.

[Stephen Siegel]

Fixed. The problem was in the verification utility class that is used to check that two models are compatible. A dynamic factory was created but never shut down. Added shut down code, including when execution exception is thrown.