* Minor improvements to CGFloat
Apparently init(exactly:) was never implemented for CGFloat, so let's fix that. Also includes minor cleanup for the .magnitude property.
* Add transparent annotations to some other CGFloat things.
These implementations did not produce the same hash values as the raw value. RawRepresentable provides a correct hashing implementation by default, so let’s just use that.
Protocols in resilient libraries that wish to provide a default implementation of hashing need to do so by providing a hash(into:) implementation.
hashValue has been deprecated as a Hashable requirement in SE-0206. Implementing only it in a protocol extension curses conforming types to get deprecation warnings by default.
The SDK directory is now confusing as the Windows target also has a SDK
overlay. In order to make this more uniform, move the SDK directory to
Darwin which covers the fact that this covers the XNU family of OSes.
The Windows directory contains the SDK overlay for the Windows target.