SceneGraph: remove forward declaration for deprecated enum.
SceneGraph: remove forward declaration for deprecated enum.

There was no point in using it anywhere else than when passing it to the
transformation function itself.

MiUishadow/magnum,DerThorsten/magnum,DerThorsten/magnum,MiUishadow/magnum,ashimidashajia/magnum,DerThorsten/magnum,MiUishadow/magnum,ashimidashajia/magnum,MiUishadow/magnum,MiUishadow/magnum,DerThorsten/magnum,DerThorsten/magnum,ashimidashajia/magnum,ashimidashajia/magnum,ashimidashajia/magnum,MiUishadow/magnum