Stem's DescriptorReader should provide an option to provide statuses vs. status entries

When I pass a tarball of consensuses to Stem's DescriptorReader, it gives me an iterator over status entries, though I'd expect an iterator over statuses. I see the advantages of returning status entries rather than waiting until a full status is parsed. But for most use cases I'm interested in, I want the status and then maybe look into status entries.

For example, I might want to extract supported consensus versions or bandwidth weights over time; no need to look into status entries for that. The alternative, to iterate over status entries and look at every referenced status document to see if I saw that before or not, seems complicated. It probably doesn't even work for bandwidth weights which are parsed after the status entries.

Can we have a parameter in DescriptorReader to specify whether it should provide top-level documents or subdocuments? I'd even argue that top-level documents should be the default, because the DescriptorReader will mostly be used for batch processing where latency and memory consumption are not an issue. But I can see how changing the default might make other people unhappy.