title: Visual Studio 2010: add existing folder
body: <p>I want to use lots of stuff that is already created and is stored in a folder.
  In a new project I want to use that classes and just add the whole folder,
  including the folder itself to keep the project clearly arranged.</p>
  
  <p>How can I add an existing folder to a project?</p>
  
  <p>As the folder is on a concurrent versions system, I do not want to copy / move / create the files and especially the folder.</p>