* changed SDLWindow to support cursor show and hide mode while remaining NSight compatibility mode alive using both modes
 * implemented billboarding render mode in RenderComponent/-System
 * cleaned up RenderSystem code (*System instances are now only retrieved once per frame)
 * removed not used functions in CameraComponent -> camera motion is now completely done by also attaching a TransformComponent to the Entity, which has a CameraComponent
 * TransformComponents can now only be updated by the TransformSystem -> will only be recalculated once per frame and and update flag is available in each TransformComponent to query if it was updated this frame
 * CameraSystem now calculates an inverse rotation matrix for each CameraComponent when an attached TransformComponent was updated this frame
 * EditorCamera will now hide cursor while panning and rotating the camera