Extracted StringReader and StringWriter from JsonParser

Split `Internals/` folder into `Data/`, `Deserialization/`, `Serialization/`

include/ArduinoJson/Data/JsonVariantContent.hpp

@@ -0,0 +1,30 @@
+// Copyright Benoit Blanchon 2014-2016
+// MIT License
+//
+// Arduino JSON library
+// https://github.com/bblanchon/ArduinoJson
+// If you like this project, please add a star!
+
+#pragma once
+
+#include "JsonFloat.hpp"
+#include "JsonInteger.hpp"
+
+namespace ArduinoJson {
+
+// Forward declarations
+class JsonArray;
+class JsonObject;
+
+namespace Internals {
+// A union that defines the actual content of a JsonVariant.
+// The enum JsonVariantType determines which member is in use.
+union JsonVariantContent {
+  JsonFloat asFloat;     // used for double and float
+  JsonUInt asInteger;    // used for bool, char, short, int and longs
+  const char* asString;  // asString can be null
+  JsonArray* asArray;    // asArray cannot be null
+  JsonObject* asObject;  // asObject cannot be null
+};
+}
+}