With this option the (RPV) BRDF surface type is selected.
This option can be used with albedo_library in order to select a spectral albedo
or with brdf_rpv_library in order to select a BRDF function.
brdf_rpv_type surface_type_number
where surface_type_number is an integer starting from 0,
where 0 refers to a black surface and the following numbers to
the entries in the specified library.