o specify the volumes by inclusion (the normal way) instead of substraction
o make the Water-Tyvek interface a SkinSurface of the water volume
o remove specific properties of the Tyvek material (unuseful)
o make the OpticalSurface a groundfrontpainted instead of groundbackpainted
o remove the RINDEX property of the surface (unuseful now)
o remove the SPECULARSPIKE probability set to 0 as the default is 0 anyway
o idem for the BACKSCATTERING probability