we can't use a projection with infinite far as a custom
projection matrix, because this is not suited for culling.
recently a new version of setCustomProjection was added which allows
to specify both the rendering and culling projections.
By default, the demo now reflects the camera instead of the renderable.
However this can be changed via the command line. Users can now change
the backend too.
When we removed the old "ghetto bloom" demo, we ceased to have any
samples demonstrating the RenderTarget API. This demo is a fairly simple
demonstration of planar reflection.
