Allowing self-conformance for protocols

[lassejansen]

Yes, but reading Improving the UI of generics and the linked discusstion thread, it looks like the any syntax might also be source breaking eventually (with a deprecation period):

• Making existential types require an explicit keyword. This one is particularly interesting because of the source compatibility concerns. Some previous discussion of this point came up in a thread about lifting the "self or associated type" constraint on existential types.