Multiple pipelines need to share just the resources in a ResourceManager

If an annotator creates an AE to run an independent pipeline with a different typesystem it can't reuse the RM as the CasManager's merged typesystem cannot be updated. We should be able to create a child RM that shares the resources (delegates to the parent?) but has a unique CasManager. The 5-arg RM constructor used for pears can be used but it requires access to maps that are protected in the existing RM. Perhaps we could add:a method such as:
ResourceManager createChild();
Destoying a child RM should not affect the parent and vice-versa.