title: Unity Project doesn't have solution file
body: <p>I just started learning unity and I created a project. But my project doesn't have a sln file included in. Every time I create a C# script and open it in Xamarin Studio I can't have any intellisense.</p>
  
  <ol>
  <li>Is it normal not to have sln file in unity project?</li>
  <li>If not, how can I add solution file to project?</li>
  <li>Why that happened?</li>
  </ol>