title: Generic List.Join
body: <p>I have an object </p>
  
  <pre><code>public class Title
      {
          public int Id {get; set; }
          public string Title {get; set; }
      }
  </code></pre>
  
  <p>How to join all Title with "-" in a <code>List&lt;Title&gt;</code> ?</p>