Merge remote repo native into ext/native/.

ext/native/json/json_writer_test.cpp

@@ -0,0 +1,25 @@
+#include "json/json_writer.h"
+#include <iostream>
+
+int main() {
+  JsonWriter j;
+  j.begin();
+  j.pushDict("settings");
+  j.writeInt("volume", 50);
+  j.writeInt("sound", 60);
+  j.pop();
+  j.pushDict("user");
+  j.writeFloat("level", 1.5);
+  j.writeString("name", "hello");
+  j.pop();
+  j.writeInt("outer", 3);
+  j.pushArray("ints");
+  j.writeInt(3);
+  j.writeInt(4);
+  j.writeInt(6);
+  j.pop();
+  j.writeString("yo!", "yo");
+  j.end();
+  std::cout << j.str();
+  return 0;
+}