This can be used for example to organize all following targets into one
Visual Studio folder:
set(CMAKE_FOLDER Libraries)
add_subdirectory(libA)
add_subdirectory(libB)
set(CMAKE_FOLDER Executables)
add_subdirectory(progA)
Another possibility is using the current directory name for all
following targets in subdirectories:
get_filename_component(dirname "${CMAKE_CURRENT_SOURCE_DIR}" NAME)
string(APPEND CMAKE_FOLDER "/${dirname}")
