* Moving into a namespace makes it easier to give the structs non-clumsy
names while still being unique and not overlapping with the other API
pipeline states.
* This gives a little nicer syntax, a bit better type safety, and also
reflects better for SWIG bindings. Overall it's a minor change but
better.
* We don't update the C# UI at all, since it's soon to be removed and
not worth the effort/code churn.
* For now so we're ABI compatible with C#, all enums are uint32_t, but
that is an obvious optimisation in future to reduce struct packing.
* We avoid 'None' as an enum value, because it's a reserved word in
python so will cause problems generating bindings.
baldurk