[Pitch #3] Property wrappers (formerly known as Property Delegates)

[Douglas_Gregor]

@George

I'm wondering why this change was added. It seems at the very least we should limit property wrappers to start with a capital letter (or _, followed by a capital letter) to prevent attribute name collisions in the future (since attributes are usually spelt with a lowercase letter)

This restriction got a bunch of push-back during the first review because we don't have casing-like restrictions anywhere else in the language.

Doug