title: Include/Exclude files per visual studio configuration
body: <p>I have multiple folders in a visual studio project. I also have the same amount of configurations for this project. (One code base runs multiple sites).</p>
  
  <p>I only want one folder per configuration to be included.</p>
  
  <p>Right now, every configuration includes every single folder.  Then, I have to manually delete the extra folders after build (if I so choose).</p>
  
  <p>This also slows down our continuous integration builds, because all the extra files it has to process.</p>
  
  <p>This cannot be achieved by the "Exclude From Project" / "Include In Project" context menu item.  That would remove it from the whole project completely.</p>
  
  <p>I need certain folders included only for certain configurations.</p>
  
  <p>X Code (iOS devleopment) handles this by using "Target Memberships"... You can tell a certain file to only be included in a certain target.</p>
  
  <p>Trying to do the same in VS.</p>
  
  <p>Please help!!</p>