Little-endian assumptions

[lrettig]

There are probably a bunch of places where we assume LE byte order, and I doubt athena would work on a native BE host today without some fixes. Opening an issue to document this and so we're aware of it. See #137 (comment) and also risc0/risc0#420 (we are not alone here).

[jellonek]

So this task is about finding all such places and cover them using https://docs.rs/byteorder/latest/byteorder/type.NativeEndian.html

[lrettig]

Right, but remember that the byte order for compiled Athena programs must be LE, and also that we use LE in serialization.