-r options should probably use xxd format for convenience

[jcrowgey]

Currently we print hex and spaces between every 4 bytes. You can | tr -d ' ' | xxd -rp | xxd to get to a regular hex dump format. I suppose it would be nice to at least ditch the spaces and just wrap newlines every 64 chars. But, maybe we should go whole hog and do the fully featured xxd format complete with ascii on the right.