Header length is encoded as little-endian, whereas network byte order is big-endian

[harmanpa]

The methods in util.py use little-endian encoding, network ordering / msgpack / Java / Javascript are all big-endian, so this may be more appropriate?

[xogeny]

Agreed. I just wanted to avoid native. But in looking at the documentation for the struct module, I clearly should have paid attention to network order.

I'll fix this right away. Fortunately, it is all contained in one place.