Possible changes to NDArray and NDArrayPool

[MarkRivers]

Statement of the problem:
NDArrays cannot be modified by plugins because a pointer is passed to each plugin
Many plugins only need to modify the attribute list, not the NDArray. But they must currently copy the entire NDArray to modify the attribute list.
Make a new container class:
NDArrayContaininer {
NDArray *pArray;
NDAttributeList *pAttributeList;
}
Container is now what gets passed to plugins. NDArray still cannot be modified. But pAttributeList can be copied and modified.
Plugin passes new container to other plugins down the chain.

[anjohnson]

Do the NDArray and NDAttributeList objects both have some kind of reference counter inside them? Keeping track of the ownership of these objects could be tricky if they can get passed from plugin to plugin and sometimes replaced. I would suggest making use of some kind of smart pointer (std::tr1::shared_ptr) for these objects instead of using raw pointers. If R3-0 is going to be based on a pvData objects then you will definitely have the shared_ptr template available, it is used quite a bit in the V4 modules.