dirstate: subclass the new dirstate Protocol class Behold the chaos that ensues. We'll use the generated *.pyi files to apply type annotations to the interface, and see how much agrees with the documentation. Since the CamelCase name was used to try to work around pytype issues with zope interfaces and is a new innovation this cycle (see c1d7ac70980b), drop the CamelCase name. I think the Protocol classes *should* be CamelCase, but that can be done later in one pass. For now, the CamelCase alias is extra noise in the *.pyi files.