title: linq distinct or group by multiple properties
body: <p>How can I using c# and Linq to get a <code>result</code> from the next list:</p>
  
  <pre><code> var pr = new List&lt;Product&gt;()
     {
         new Product() {Title="Boots",Color="Red",    Price=1},
         new Product() {Title="Boots",Color="Green",  Price=1},
         new Product() {Title="Boots",Color="Black",  Price=2},
  
         new Product() {Title="Sword",Color="Gray", Price=2},
         new Product() {Title="Sword",Color="Green",Price=2}
     };
  </code></pre>
  
  <p><code>Result</code>:</p>
  
  <pre><code>        {Title="Boots",Color="Red",  Price=1},               
          {Title="Boots",Color="Black",  Price=2},             
          {Title="Sword",Color="Gray", Price=2}
  </code></pre>
  
  <p>I know that I should use <code>GroupBy</code> or <code>Distinct</code>, but understand how to get what is needed</p>
  
  <pre><code>   List&lt;Product&gt; result = pr.GroupBy(g =&gt; g.Title, g.Price).ToList(); //not working
     List&lt;Product&gt; result  = pr.Distinct(...);
  </code></pre>
  
  <p>Please help</p>