Extracted StringReader and StringWriter from JsonParser

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

include/ArduinoJson/Serialization/IndentedPrint.hpp

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+// 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 "../Print.hpp"
+
+namespace ArduinoJson {
+namespace Internals {
+
+// Decorator on top of Print to allow indented output.
+// This class is used by JsonPrintable::prettyPrintTo() but can also be used
+// for your own purpose, like logging.
+class IndentedPrint : public Print {
+ public:
+  explicit IndentedPrint(Print &p) : sink(&p) {
+    level = 0;
+    tabSize = 2;
+    isNewLine = true;
+  }
+
+  virtual size_t write(uint8_t c) {
+    size_t n = 0;
+    if (isNewLine) n += writeTabs();
+    n += sink->write(c);
+    isNewLine = c == '\n';
+    return n;
+  }
+
+  // Adds one level of indentation
+  void indent() {
+    if (level < MAX_LEVEL) level++;
+  }
+
+  // Removes one level of indentation
+  void unindent() {
+    if (level > 0) level--;
+  }
+
+  // Set the number of space printed for each level of indentation
+  void setTabSize(uint8_t n) {
+    if (n < MAX_TAB_SIZE) tabSize = n & MAX_TAB_SIZE;
+  }
+
+ private:
+  Print *sink;
+  uint8_t level : 4;
+  uint8_t tabSize : 3;
+  bool isNewLine : 1;
+
+  size_t writeTabs() {
+    size_t n = 0;
+    for (int i = 0; i < level * tabSize; i++) n += sink->write(' ');
+    return n;
+  }
+
+  static const int MAX_LEVEL = 15;    // because it's only 4 bits
+  static const int MAX_TAB_SIZE = 7;  // because it's only 3 bits
+};
+}
+}