Can Codable with optional by @OptionalKeyed

- @Keyed var id: String?
+@OptionalKeyed var id: String?

Please note Keyed var _: TYPE? will make a runtime error to tell you the disability on optional.

@Keyed can get key during run time

struct JSON: SuperCodable {
-    @Keyed("id") var id: String
+    @Keyed var id: String
}

First release

1.0.0

add test setting