title: How to write Vector of Vector of Points in a json file?
body: <p>I am a beginner in reading/writing JSON files.
  How can I write a <code>std::vector&lt;std::vector&lt;Point&gt;&gt;</code> (C++ data type) to a JSON file, such that I can access each <code>std::vector&lt;point&gt;</code> seperately, after reading the created JSON?
  Please help.</p>