title: Modify programatically csproj files with Microsoft.Build.Evaluation (instead of Engine)
body: <p>I would like to read, modify and write back csproj files.
  I've found this code, but unfortunately Engine class is depreciated. </p>
  
  <pre><code>Engine engine = new Engine()
  Project project = new Project(engine);
  project.Load("myproject.csproj");
  project.SetProperty("SignAssembly", "true");
  project.Save("myproject.csproj");
  </code></pre>
  
  <p>So I've continued based on the hint I should use Evaluation.ProjectCollection instead of Engine:</p>
  
  <pre><code>var collection = new ProjectCollection();
  collection.DefaultToolsVersion = "4.0";
  var project = new Project(collection);
  
  // project.Load("myproject.csproj") There is NO Load method :-(
  project.FullPath = "myproject.csproj"; // Instead of load? Does nothing...
  
  // ... modify the project
  project.Save(); // Interestingly there is a Save() method
  </code></pre>
  
  <p>There is no Load method anymore. I've tried to set the property FullPath, but the project still seems empty. Missed I something?</p>
  
  <p>(Please note I do know that the .csproj file is a standard XML file with XSD schema and I know that we could read/write it by using XDocument or XmlDocument. That's a backup plan. Just seeing the .Save() method on the Project class I think I missed something if I can not load an existing .csproj. thx)</p>