Make plugin wrappers inheritable

It would greatly help if we could derive our own custom wrapper classes to handle cases that the current wrappers do not. For example, the current AAX wrapper does not support CompareActiveChunk, which we need in order to compare non-parameter data when running in Pro Tools. But the current wrapper instantiation only creates that one specific class, and there is no way to derive a class from it that we can add our own customization to. A wrapper class that can easily be derived from, and a factory function for creating an instance of it, would help us greatly.