title: CMake: include_external_msproject() and mapping configurations
body: <p>I have a MSVC++ project <em>fooproj</em> that basically comes as input to the project I'm working on.  I want to use CMake to add some sanity to the work on configuration of the solution+projects.  Furthermore, I will be making changes (and contributing them back) in <em>fooproj</em> so I'd really like to properly import it into the solution that CMake generates so I'm looking at using include_external_msproject(), but I'd like to somehow control which configuration of <em>fooproj</em> I use for Debug/Release:</p>
  
  <ul>
  <li>solution-lvl Debug -> project-lvl LibDebug</li>
  <li>solution-lvl Release -> project-lvl LibRelease</li>
  </ul>
  
  <p>Currently I do this manually after regenerating the solution using the <em>Configuration Manager</em> in VS, but I'd like to make it automatic.  Is there some way to do that?</p>