title: WebClient.DownloadString uses wrong encoding
body: <p>I'm downloading XML files from sharepoint online using webclient.</p>
  
  <p>However, when I use <code>WebClient.DownloadString(string url)</code> method, some characters are not correctly decoded.</p>
  
  <p>When I use <code>WebClient.DownloadFile(string url, string file)</code> and then I read the file all characters are correct.</p>
  
  <p>The xml itself does not contain encoding declaration.</p>
  
  <pre><code>string wrongXml = webClient.DownloadString(url);
  //wrongXml contains Ä™ instead of ę
  
  webClient.DownloadFile(url, @"C:\temp\file1.xml");
  string correctXml = File.ReadAllText(@"C:\temp\file1.xml");
  //contains ę, like it should.
  </code></pre>
  
  <p>Also, when open the url in Internet Explorer, it is shown correctly.</p>
  
  <p>Why is that? Is it because of the default windows encoding on my machine or webclient handles responses differently when using DownloadString, resp DownloadFile?</p>