Returns Rendering Windows for Graphics Window Creation

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When creating a graphics window, the carrier needs to return a rendering window that has the renderer inside, so the user can render directly into the window.

motor::application::graphics_window_info_t gi ;
auto wnd = carrier->create_window( gi ) ;

// engine allows to render into the window
wnd->get_render_engine() ;

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This one changed. The renderer is now created along with a normal window. The engine is not used for any other purpose than rendering to the screen. So introducing another window type is just more boiler plate.