Refactor XsdNonLocalElement unapply

[bbarker]

I attempted to do this like so to remove some code duplication:

    @mutualrec
    final def lastMatch(last: Option[(String, Try[NodeWrap])], eArgs: EnumArgs): Option[(String, Try[NodeWrap])]  = last match {
      case Some((labelCarry: String, Success(node: NodeWrap)))
        if !isLocallyDefined(node.node) =>
        // Keep chasing the reference
        //TODO: above, need to check to see if we need worry about non-head elements
        unapply(NodeWrapCarry(node.node.child.head, eArgs, labelCarry))
      case _ => last
    }

    //    def unapply(arg: Node, eArgs: EnumArgs): Option[(String, Try[Node])] =
    //      unapply(NodeWrap(arg, eArgs))
    //
    //TODO: also looking up arg.fullName is not sufficient... need whole xpath?
    @mutualrec
    final def unapply(arg0: NodeWrapAbstract): Option[(String, Try[NodeWrap])] = {

      val (last, eArgs) = arg0 match {
        case argNW@NodeWrap(arg: Node, eArgs: EnumArgs) =>
          (unapplyMatcher(argNW, ""), eArgs)
        case NodeWrapCarry(arg: Node, eArgs: EnumArgs, label: String) =>
          (unapplyMatcher(NodeWrap(arg, eArgs), label), eArgs)
      }
      lastMatch(last, eArgs)
    }
  }

However, this results in "Unable to tail call optimize as this is either not effectively final or a non-constructor method". The issue appears to be that different signatures in the mutual methods are not supported, currently a scalac convention.