Added finalizers to image. Use browser image preloading for emscripten target.
Added finalizers to image. Use browser image preloading for emscripten target.

bogdan-voevoda/nimx,rrenderr/nimx,qqquinta/nimx,yglukhov/nimx,qqquinta/nimx,qqquinta/nimx,yglukhov/nimx,yglukhov/nimx,bogdan-voevoda/nimx,rrenderr/nimx,rrenderr/nimx,bogdan-voevoda/nimx