Add debug postfix for main executables on Windows platform. Closes #113.

Source/CMake/Modules/Urho3D-CMake-magic.cmake

@@ -513,6 +513,9 @@ macro (setup_main_executable)
             setup_macosx_linker_flags (CMAKE_EXE_LINKER_FLAGS)
         endif ()
         setup_executable (${EXE_TYPE})
+        if (WIN32)
+            set_target_properties (${TARGET_NAME} PROPERTIES DEBUG_POSTFIX _d)
+        endif ()
     endif ()
     
     if (IOS)