Class to wrap a OpenCVFilter, but to hide its type. Otherwise all
OpenCVFilter types would need to be stubbed out in the OpenCV
service. This way the OpenCV is oblivious to the type - making invoke
This does a setFilterState - shallow copy which is a reflective copy
of data variables, very handy, but will be problematic for any JNI or
pointer structures - these MUST be marked transient !