message: Add Void Reader to reader_struct
  This gives an easy way to disable reading some chunks,
  for memory profiling
diff: @@ -52,7 +52,8 @@ struct Category {
  Primitive,
  Struct,
  Flags,
  - RawStruct
  + RawStruct,
  + Void
  };
  };
  @@ -94,6 +95,30 @@ struct TypeCategory<std::vector<T>> {
  template <class T, Category::Index cat = TypeCategory<T>::value>
  struct TypeReader {};
  +
  +/**
  + * Void reader template.
  + */
  +
  +template <class T>
  +struct TypeReader<T, Category::Void> {
  + static void ReadLcf(T& ref, LcfReader& stream, uint32_t length) {
  + stream.Seek(length, LcfReader::FromCurrent);
  + }
  + static void WriteLcf(const T& ref, LcfWriter& stream) {
  + }
  + static int LcfSize(const T& ref, LcfWriter& stream) {
  + return 0;
  + }
  + static void WriteXml(const T& ref, XmlWriter& stream) {
  + }
  + static void BeginXml(T& ref, XmlReader& stream) {
  + }
  + static void ParseXml(T& /* ref */, const std::string& /* data */) {
  + //no-op
  + }
  +};
  +
  /**
  * Raw structure reader template.
  */
  