Release input devices when application is shutdown

If they are released with the deallocation of CInputManager, we might
run into global deallocation hell.
Also on Windows release all DirectX devices before COM library is closed.

ref T391

src/blackcore/inputmanager.h

@@ -87,6 +87,9 @@ namespace BlackCore
         //! Triggers a key event manually and calls the registered functions.
         void triggerKey(const BlackMisc::Input::CHotkeyCombination &combination, bool isPressed);
 
+        //! Releases all devices
+        void releaseDevices();
+
         //! Creates a native keyboard handler object
         static CInputManager *instance();