title: Case insensitive std::set of strings
body: <p>How do you have a case insensitive insertion Or search of a string in std::set?</p>
  
  <p>For example-</p>
  
  <pre><code>std::set&lt;std::string&gt; s;
  s.insert("Hello");
  s.insert("HELLO"); //not allowed, string already exists.
  </code></pre>