Concatenating afwTable catalogs to create one catalog with contiguous memory isn't quite as simple as it should be. One reason is that the reserve() member doesn't do what you might expect as it makes no guarantee of contiguous storage [this is why std::deque::reserve doesn't exist].

We should provide a utility function that does this right (Jim tells me that there is a right way – I know a variety of ways that work that don't quite work when you allow for things like slots, or that require a deep copy of the result)