msvc: Use source folder structure for project file.

This patch changes the huge list of projects in visual studio into a nice tree matching the source folder structure. see D2823 for details.

Differential Revision: http://developer.blender.org/D2823

CMakeLists.txt

@@ -544,6 +544,9 @@ if(WIN32)
 
 	set(WINDOWS_CODESIGN_PFX_PASSWORD CACHE STRING  "password for pfx file used for codesigning.")
 	mark_as_advanced(WINDOWS_CODESIGN_PFX_PASSWORD)
+
+	option(WINDOWS_USE_VISUAL_STUDIO_FOLDERS "Organize the visual studio project according to source folders." ON)
+	mark_as_advanced(WINDOWS_USE_VISUAL_STUDIO_FOLDERS)
 endif()
 
 # avoid using again