[noise] Protocol Names

[Jason A. Donenfeld]

Hey Jake,

In my opinion, being able to put the modifier right next to the
pattern makes it look a bit prettier in the case of a single modifier
-- "IKpsk2", for example. I'm a bit biased, of course, since I've
already deployed code using this, as has WhatsApp.

I'd recommend always sorting the modifiers alphabetically, and
considering it to be an error / spec-violation to send no-alphabetized
modifiers. The sole exception would be for non-commutative modifiers,
which then go in their right place. The algorithm for doing this is
pretty simple.

Handshake names can be separated from modifiers by just requiring
uppercase/lowercase, as you mentioned.

In the case of primitive modifiers, these aren't really parsable,
anyway, since they correspond to exact implementations. At this point,
I think it makes sense to consider modifiers of primitives to be
particular for each primitive, rather than generic. Assuming this, the
parsing remains easy.

Jason