Configuration specific install directories for the ExternalProject module.
Currently if I use a generator that supports multiple configurations (XCode, VisualStudio), the ExternalProject's build in separate directories (as they inherit the generator), but they install in the same directory. Which for most platforms isn't much of an issue (although not ideal). However with VisualStudio this posses a major issue as you can't mix debug and release builds.. Thus if I have previously been working on a debug build of a project and then trigger a release, odds are it will link with the debug builds in the External project "install" dir causing link errors.. The only way to fix this is to do a complete clean and rebuild which is time consuming.