codecgen: special-case (en|de)coding where underlying type is []byte or [N]byte
codecgen: special-case (en|de)coding where underlying type is []byte or [N]byte

when we generate a method for a type whose underlying type is slice or array of bytes,
we will call the special-case EncodeStringBytes or DecodeBytes respectively.

Fixes #165

ugorji/go,ugorji/go,ugorji/go