Add coproduct codec builder derivation
Merge branch 'master' into topic/shapeless-2.1
Generalize coproduct codec derivation to prepare for unions; align naming with shapeless
Merge branch 'master' into topic/shapeless-2.1
Add support for unions to auto coproduct codec builders
Add support for autogenerated coproduct codec builders for sealed case class like hierarchies
Merge branch 'master' into topic/shapeless-2.1

Conflicts:
	src/main/scala/scodec/Codec.scala