Signed and unsigned don't quite capture the essence of what the different
combinations of x86 flags are doing for SubX. The crucial distinction is
that one set of comparison operators is for integers and the second is
for addresses.
When I created it I was conflating two things:
a) needing to refer to just the start, rather than the whole, and
b) counting indirections.
Both are kinda ill-posed. Now Mu will have just `addr` and `handle` types.
Normal types will translate implicitly to `addr` types, while `handle`
will always require explicit handling.
Kartik Agaram