circe 0.4.1

0.4.1 is a bug-fix release that backports #273 to fix an issue where semi-automatic derivation would fail on some generic types:

scala> import io.circe._, io.circe.generic.semiauto._
import io.circe._
import io.circe.generic.semiauto._

scala> case class Foo[A](a: A)
defined class Foo

scala> implicit def decodeFoo[A: Decoder]: Decoder[Foo[A]] = deriveDecoder
<console>:19: error: could not find Lazy implicit value of type io.circe.generic.decoding.DerivedDecoder[A]
       implicit def decodeFoo[A: Decoder]: Decoder[Foo[A]] = deriveDecoder
                                                             ^

The only affected module is circe-generic, and the fix does not break binary compatibility.