Changed how NoiseTexture is created to allow noise function and
parameters to be passed in as options.
Allowed setting of noise source from URL parameters.
Use of generic parameter directly where possible in structures instead
of Box'd values.
Added Material implementations for Box<Material> and Arc<Material> to
aid in the automatic conversion when necessary to use a Sized value for
Material.
Implement From trait for [f32;3] to Vec3 to make some APIs Into<Vec3>
which is a bit nicer to use.
