title: Different configuaration string for specific build configuration
body: <p>how can i configure my Visual Studio 2010 C# solution/project so 
  that when i select a Debug configuration - ConnectionString#1 would be used
  Release - Connection string #2
  and
  "Myconfiguarion1" (which was copied from debug) -> Connection string #3</p>
  
  <p>I got to it work with debug in such a way:</p>
  
  <pre><code>if (ConfigurationManager.ConnectionStrings["ConnectionString1"] != null)
  {
      winApplication.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString1"].ConnectionString;
  }
  
  #if DEBUG
  if(ConfigurationManager.ConnectionStrings["ConnectionString2"] != null) 
  {
      winApplication.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString2"].ConnectionString;
  }
  #endif
  </code></pre>
  
  <p>but this doesn't work with "MybuildConfiguration"</p>